diff --git a/exercises/advanced_errors/advanced_errs1.rs b/exercises/advanced_errors/advanced_errs1.rs
index 4bc7b635..6dda9fb7 100644
--- a/exercises/advanced_errors/advanced_errs1.rs
+++ b/exercises/advanced_errors/advanced_errs1.rs
@@ -24,12 +24,18 @@ impl From<CreationError> for ParsePosNonzeroError {
     fn from(e: CreationError) -> Self {
         // TODO: complete this implementation so that the `?` operator will
         // work for `CreationError`
+        Self::Creation(e)
     }
 }
 
 // TODO: implement another instance of the `From` trait here so that the
 // `?` operator will work in the other place in the `FromStr`
 // implementation below.
+impl From<ParseIntError> for ParsePosNonzeroError {
+    fn from(e: ParseIntError) -> Self {
+        Self::ParseInt(e)
+    }
+}
 
 // Don't change anything below this line.
 
diff --git a/exercises/advanced_errors/advanced_errs2.rs b/exercises/advanced_errors/advanced_errs2.rs
index d9d44d06..5204c38a 100644
--- a/exercises/advanced_errors/advanced_errs2.rs
+++ b/exercises/advanced_errors/advanced_errs2.rs
@@ -47,9 +47,14 @@ impl From<ParseIntError> for ParseClimateError {
 impl From<ParseFloatError> for ParseClimateError {
     fn from(e: ParseFloatError) -> Self {
         // TODO: Complete this function
+        Self::ParseFloat(e)
     }
 }
 
+impl std::error::Error for ParseClimateError {
+
+}
+
 // TODO: Implement a missing trait so that `main()` below will compile. It
 // is not necessary to implement any methods inside the missing trait.
 
@@ -63,7 +68,10 @@ impl Display for ParseClimateError {
         use ParseClimateError::*;
         match self {
             NoCity => write!(f, "no city name"),
+            BadLen => write!(f, "incorrect number of fields"),
+            Empty => write!(f, "empty input"),
             ParseFloat(e) => write!(f, "error parsing temperature: {}", e),
+            ParseInt(e) => write!(f, "error parsing year: {}", e),
             _ => write!(f, "unhandled error!"),
         }
     }
@@ -90,11 +98,19 @@ impl FromStr for Climate {
     // cases.
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let v: Vec<_> = s.split(',').collect();
-        let (city, year, temp) = match &v[..] {
+        let (city, yr, temp) = match &v[..] {
             [city, year, temp] => (city.to_string(), year, temp),
+            [""] => return Err(ParseClimateError::Empty),
             _ => return Err(ParseClimateError::BadLen),
         };
-        let year: u32 = year.parse()?;
+        if city.is_empty() {
+            return Err(ParseClimateError::NoCity);
+        }
+        let year: u32;
+        match yr.parse::<u32>() {
+            Ok(y) => year = y,
+            Err(e) => return Err(ParseClimateError::ParseInt(e))
+        }
         let temp: f32 = temp.parse()?;
         Ok(Climate { city, year, temp })
     }
diff --git a/exercises/clippy/clippy2.rs b/exercises/clippy/clippy2.rs
index 37af9ed0..352c4e16 100644
--- a/exercises/clippy/clippy2.rs
+++ b/exercises/clippy/clippy2.rs
@@ -6,7 +6,7 @@
 fn main() {
     let mut res = 42;
     let option = Some(12);
-    for x in option {
+    if let Some(x) = option {
         res += x;
     }
     println!("{}", res);
diff --git a/exercises/collections/hashmap1.rs b/exercises/collections/hashmap1.rs
index 64b5a7f3..e4dbf8b4 100644
--- a/exercises/collections/hashmap1.rs
+++ b/exercises/collections/hashmap1.rs
@@ -16,12 +16,14 @@
 use std::collections::HashMap;
 
 fn fruit_basket() -> HashMap<String, u32> {
-    let mut basket = // TODO: declare your hash map here.
+    let mut basket = HashMap::new();
 
     // Two bananas are already given for you :)
     basket.insert(String::from("banana"), 2);
 
     // TODO: Put more fruits in your basket here.
+    basket.insert(String::from("apple"), 2);
+    basket.insert(String::from("peach"), 3);
 
     basket
 }
diff --git a/exercises/collections/hashmap2.rs b/exercises/collections/hashmap2.rs
index 0abe19ab..95c9ffdf 100644
--- a/exercises/collections/hashmap2.rs
+++ b/exercises/collections/hashmap2.rs
@@ -38,6 +38,7 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
         // TODO: Put new fruits if not already present. Note that you
         // are not allowed to put any type of fruit that's already
         // present!
+        basket.entry(fruit).or_insert(1);
     }
 }
 
diff --git a/exercises/collections/vec1.rs b/exercises/collections/vec1.rs
index b144fb94..88035b73 100644
--- a/exercises/collections/vec1.rs
+++ b/exercises/collections/vec1.rs
@@ -8,7 +8,7 @@
 
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    let v = vec![10, 20, 30, 40];// TODO: declare your vector here with the macro for vectors
 
     (a, v)
 }
diff --git a/exercises/collections/vec2.rs b/exercises/collections/vec2.rs
index 6595e401..da31812e 100644
--- a/exercises/collections/vec2.rs
+++ b/exercises/collections/vec2.rs
@@ -13,6 +13,7 @@ fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for i in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
+        *i *= 2
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
diff --git a/exercises/conversions/as_ref_mut.rs b/exercises/conversions/as_ref_mut.rs
index 84f4a60c..68325668 100644
--- a/exercises/conversions/as_ref_mut.rs
+++ b/exercises/conversions/as_ref_mut.rs
@@ -6,13 +6,15 @@
 
 // Obtain the number of bytes (not characters) in the given argument
 // Add the AsRef trait appropriately as a trait bound
-fn byte_counter<T>(arg: T) -> usize {
+fn byte_counter<T>(arg: T) -> usize 
+    where T: AsRef<str> {
     arg.as_ref().as_bytes().len()
 }
 
 // Obtain the number of characters (not bytes) in the given argument
 // Add the AsRef trait appropriately as a trait bound
-fn char_counter<T>(arg: T) -> usize {
+fn char_counter<T>(arg: T) -> usize
+    where T: AsRef<str> {
     arg.as_ref().chars().count()
 }
 
diff --git a/exercises/conversions/from_into.rs b/exercises/conversions/from_into.rs
index 9d84174d..90e0dc91 100644
--- a/exercises/conversions/from_into.rs
+++ b/exercises/conversions/from_into.rs
@@ -37,6 +37,24 @@ impl Default for Person {
 
 impl From<&str> for Person {
     fn from(s: &str) -> Person {
+        let v: Vec<_> = s.split(",").collect();
+        // println!("{:?}", v);
+        let (name, age) = match &v[..] {
+            ["", _] => return Default::default(),
+            [_, ""] => return Default::default(),
+            [name, age] => (name.to_string(), age),
+            _ => return Default::default()
+        };
+
+        let age: usize = match age.parse() {
+            Ok(age) => age,
+            _ => return Default::default()
+        };
+
+        Self {
+            name,
+            age
+        }
     }
 }
 
diff --git a/exercises/conversions/from_str.rs b/exercises/conversions/from_str.rs
index ece0b3cf..e9c60e07 100644
--- a/exercises/conversions/from_str.rs
+++ b/exercises/conversions/from_str.rs
@@ -41,6 +41,22 @@ enum ParsePersonError {
 impl FromStr for Person {
     type Err = ParsePersonError;
     fn from_str(s: &str) -> Result<Person, Self::Err> {
+        let v: Vec<_> = s.split(",").collect();
+        let (name, age) = match &v[..] {
+            [""] => return Err(ParsePersonError::Empty),
+            ["", _] => return Err(ParsePersonError::NoName),
+            [name, age] => (name.to_string(), age),
+            _ => return Err(ParsePersonError::BadLen)
+        };
+
+        let age: usize = match age.parse() {
+            Ok(age) => age,
+            Err(e) => return Err(ParsePersonError::ParseInt(e))
+        };
+
+        Ok(Self {
+            name, age
+        })
     }
 }
 
diff --git a/exercises/conversions/try_from_into.rs b/exercises/conversions/try_from_into.rs
index b8ec4455..efd095e2 100644
--- a/exercises/conversions/try_from_into.rs
+++ b/exercises/conversions/try_from_into.rs
@@ -36,6 +36,24 @@ enum IntoColorError {
 impl TryFrom<(i16, i16, i16)> for Color {
     type Error = IntoColorError;
     fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {
+        let red = match u8::try_from(tuple.0) {
+            Ok(red) => red,
+            _ => return Err(Self::Error::IntConversion),
+        };
+
+        let green = match u8::try_from(tuple.1) {
+            Ok(green) => green,
+            _ => return Err(Self::Error::IntConversion),
+        };
+
+        let blue = match u8::try_from(tuple.2) {
+            Ok(blue) => blue,
+            _ => return Err(Self::Error::IntConversion),
+        };
+
+        Ok(Self {
+            red, green, blue
+        })
     }
 }
 
@@ -43,6 +61,7 @@ impl TryFrom<(i16, i16, i16)> for Color {
 impl TryFrom<[i16; 3]> for Color {
     type Error = IntoColorError;
     fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {
+        Self::try_from((arr[0], arr[1], arr[2]))
     }
 }
 
@@ -50,6 +69,11 @@ impl TryFrom<[i16; 3]> for Color {
 impl TryFrom<&[i16]> for Color {
     type Error = IntoColorError;
     fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {
+        if slice.len() != 3 {
+            return Err(Self::Error::BadLen);
+        }
+
+        Self::try_from((slice[0], slice[1], slice[2]))
     }
 }
 
diff --git a/exercises/conversions/using_as.rs b/exercises/conversions/using_as.rs
index 821309ec..5aabe4ad 100644
--- a/exercises/conversions/using_as.rs
+++ b/exercises/conversions/using_as.rs
@@ -9,7 +9,7 @@
 
 fn average(values: &[f64]) -> f64 {
     let total = values.iter().fold(0.0, |a, b| a + b);
-    total / values.len()
+    total / (values.len() as f64)
 }
 
 fn main() {
diff --git a/exercises/enums/enums1.rs b/exercises/enums/enums1.rs
index a2223d33..9301c20a 100644
--- a/exercises/enums/enums1.rs
+++ b/exercises/enums/enums1.rs
@@ -6,6 +6,10 @@
 #[derive(Debug)]
 enum Message {
     // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor,
 }
 
 fn main() {
diff --git a/exercises/enums/enums2.rs b/exercises/enums/enums2.rs
index ec32d952..c8d56671 100644
--- a/exercises/enums/enums2.rs
+++ b/exercises/enums/enums2.rs
@@ -6,6 +6,10 @@
 #[derive(Debug)]
 enum Message {
     // TODO: define the different variants used below
+    Move {x: i32, y: i32},
+    Echo (String),
+    ChangeColor (i32, i32, i32),
+    Quit,
 }
 
 impl Message {
diff --git a/exercises/enums/enums3.rs b/exercises/enums/enums3.rs
index 178b40c4..27455fb6 100644
--- a/exercises/enums/enums3.rs
+++ b/exercises/enums/enums3.rs
@@ -2,11 +2,15 @@
 // Address all the TODOs to make the tests pass!
 
 // I AM NOT DONE
-
+#[derive(Debug)]
 enum Message {
     // TODO: implement the message variant types based on their usage below
+    ChangeColor((u8, u8, u8)),
+    Echo(String),
+    Move(Point),
+    Quit,
 }
-
+#[derive(Debug)]
 struct Point {
     x: u8,
     y: u8,
@@ -37,6 +41,20 @@ impl State {
 
     fn process(&mut self, message: Message) {
         // TODO: create a match expression to process the different message variants
+        match message {
+            Message::ChangeColor((x, y, z)) => {
+                self.color = (x, y, z);
+            },
+            Message::Move(p) => {
+                self.position = p;
+            },
+            Message::Quit => {
+                self.quit = true;
+            },
+            Message::Echo(s) => {
+                println!("{}", s);
+            }
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors1.rs b/exercises/error_handling/errors1.rs
index 9c24d85d..9a478b60 100644
--- a/exercises/error_handling/errors1.rs
+++ b/exercises/error_handling/errors1.rs
@@ -8,12 +8,12 @@
 
 // I AM NOT DONE
 
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.len() > 0 {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     } else {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".to_string())
     }
 }
 
@@ -28,7 +28,7 @@ mod tests {
     fn generates_nametag_text_for_a_nonempty_name() {
         assert_eq!(
             generate_nametag_text("Beyoncé".into()),
-            Some("Hi! My name is Beyoncé".into())
+            Ok("Hi! My name is Beyoncé".into())
         );
     }
 
diff --git a/exercises/error_handling/errors2.rs b/exercises/error_handling/errors2.rs
index aad3a93f..444ca4d6 100644
--- a/exercises/error_handling/errors2.rs
+++ b/exercises/error_handling/errors2.rs
@@ -23,9 +23,12 @@ use std::num::ParseIntError;
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>();
-
-    Ok(qty * cost_per_item + processing_fee)
+    match item_quantity.parse::<i32>() {
+        Ok(qty) => {
+            Ok(qty * cost_per_item + processing_fee)
+        },
+        e => e
+    }
 }
 
 #[cfg(test)]
diff --git a/exercises/error_handling/errors3.rs b/exercises/error_handling/errors3.rs
index 460ac5c4..6972fb63 100644
--- a/exercises/error_handling/errors3.rs
+++ b/exercises/error_handling/errors3.rs
@@ -12,7 +12,7 @@ fn main() {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
-    let cost = total_cost(pretend_user_input)?;
+    let cost = total_cost(pretend_user_input).unwrap();
 
     if cost > tokens {
         println!("You can't afford that many!");
@@ -25,7 +25,8 @@ fn main() {
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
-    let qty = item_quantity.parse::<i32>()?;
-
-    Ok(qty * cost_per_item + processing_fee)
+    match item_quantity.parse::<i32>() {
+        Ok(qty) => Ok(qty * cost_per_item + processing_fee),
+        e => e
+    }
 }
diff --git a/exercises/error_handling/errors4.rs b/exercises/error_handling/errors4.rs
index 0685c374..d828dcd5 100644
--- a/exercises/error_handling/errors4.rs
+++ b/exercises/error_handling/errors4.rs
@@ -14,7 +14,13 @@ enum CreationError {
 
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value < 0 {
+            Err(CreationError::Negative)
+        } else if value == 0 {
+            Err(CreationError::Zero)
+        } else {
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
     }
 }
 
diff --git a/exercises/error_handling/errors5.rs b/exercises/error_handling/errors5.rs
index 365a8691..a7499f41 100644
--- a/exercises/error_handling/errors5.rs
+++ b/exercises/error_handling/errors5.rs
@@ -11,7 +11,7 @@ use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), ParseIntError> {
+fn main() -> Result<(), Box<dyn error::Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);
diff --git a/exercises/error_handling/errors6.rs b/exercises/error_handling/errors6.rs
index 0f6b27a6..772e0f35 100644
--- a/exercises/error_handling/errors6.rs
+++ b/exercises/error_handling/errors6.rs
@@ -24,6 +24,9 @@ impl ParsePosNonzeroError {
         ParsePosNonzeroError::Creation(err)
     }
     // TODO: add another error conversion function here.
+    fn from_parseint(err: ParseIntError) -> ParsePosNonzeroError {
+        ParsePosNonzeroError::ParseInt(err)
+    }
 }
 
 fn parse_pos_nonzero(s: &str)
@@ -31,9 +34,15 @@ fn parse_pos_nonzero(s: &str)
 {
     // TODO: change this to return an appropriate error instead of panicking
     // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
-    PositiveNonzeroInteger::new(x)
-        .map_err(ParsePosNonzeroError::from_creation)
+    match s.parse() {
+        Ok(x) => {
+            match PositiveNonzeroInteger::new(x) {
+                Ok(pni) => Ok(pni),
+                Err(e) => Err(ParsePosNonzeroError::from_creation(e))
+            }
+        },
+        Err(e) => Err(ParsePosNonzeroError::from_parseint(e))
+    }
 }
 
 // Don't change anything below this line.
diff --git a/exercises/functions/functions1.rs b/exercises/functions/functions1.rs
index 31125278..176aed97 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -3,6 +3,10 @@
 
 // I AM NOT DONE
 
+fn call_me() {
+    
+}
+
 fn main() {
     call_me();
 }
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 5721a172..d493ca65 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -7,7 +7,7 @@ fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num: i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/functions/functions3.rs b/exercises/functions/functions3.rs
index ed5f839f..18ef5436 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -4,7 +4,7 @@
 // I AM NOT DONE
 
 fn main() {
-    call_me();
+    call_me(3);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/functions/functions4.rs b/exercises/functions/functions4.rs
index 58637e4c..ac3b8ef9 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -11,7 +11,7 @@ fn main() {
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {
diff --git a/exercises/functions/functions5.rs b/exercises/functions/functions5.rs
index d22aa6c8..d4ceceed 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -9,5 +9,5 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    num * num
 }
diff --git a/exercises/generics/generics1.rs b/exercises/generics/generics1.rs
index f93e64a0..0c234aff 100644
--- a/exercises/generics/generics1.rs
+++ b/exercises/generics/generics1.rs
@@ -6,6 +6,6 @@
 // I AM NOT DONE
 
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list: Vec<&str> = Vec::new();
     shopping_list.push("milk");
 }
diff --git a/exercises/generics/generics2.rs b/exercises/generics/generics2.rs
index 1501529c..2225860d 100644
--- a/exercises/generics/generics2.rs
+++ b/exercises/generics/generics2.rs
@@ -5,12 +5,12 @@
 
 // I AM NOT DONE
 
-struct Wrapper {
-    value: u32,
+struct Wrapper<T> {
+    value: T,
 }
 
-impl Wrapper {
-    pub fn new(value: u32) -> Self {
+impl<T> Wrapper<T> {
+    pub fn new(value: T) -> Self {
         Wrapper { value }
     }
 }
diff --git a/exercises/generics/generics3.rs b/exercises/generics/generics3.rs
index 64dd9bc1..f3dc9988 100644
--- a/exercises/generics/generics3.rs
+++ b/exercises/generics/generics3.rs
@@ -12,13 +12,13 @@
 
 // I AM NOT DONE
 
-pub struct ReportCard {
-    pub grade: f32,
+pub struct ReportCard<T> {
+    pub grade: T,
     pub student_name: String,
     pub student_age: u8,
 }
 
-impl ReportCard {
+impl<T: std::fmt::Display> ReportCard<T> {
     pub fn print(&self) -> String {
         format!("{} ({}) - achieved a grade of {}",
             &self.student_name, &self.student_age, &self.grade)
@@ -46,7 +46,7 @@ mod tests {
     fn generate_alphabetic_report_card() {
         // TODO: Make sure to change the grade here after you finish the exercise.
         let report_card = ReportCard {
-            grade: 2.1,
+            grade: "A+",
             student_name: "Gary Plotter".to_string(),
             student_age: 11,
         };
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 90867545..9efe170c 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -8,6 +8,11 @@ pub fn bigger(a: i32, b: i32) -> i32 {
     // - another function call
     // - additional variables
     // Execute `rustlings hint if1` for hints
+    if a > b {
+        a
+    } else {
+        b
+    }
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index 80effbdf..4c1c1ee6 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -9,8 +9,10 @@
 pub fn fizz_if_foo(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 
diff --git a/exercises/macros/macros1.rs b/exercises/macros/macros1.rs
index ed0dac85..2ffe5202 100644
--- a/exercises/macros/macros1.rs
+++ b/exercises/macros/macros1.rs
@@ -3,6 +3,7 @@
 
 // I AM NOT DONE
 
+#[macro_export]
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
@@ -10,5 +11,5 @@ macro_rules! my_macro {
 }
 
 fn main() {
-    my_macro();
+    my_macro!();
 }
diff --git a/exercises/macros/macros2.rs b/exercises/macros/macros2.rs
index d0be1236..bd8e5f1a 100644
--- a/exercises/macros/macros2.rs
+++ b/exercises/macros/macros2.rs
@@ -7,6 +7,7 @@ fn main() {
     my_macro!();
 }
 
+#[macro_export]
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
diff --git a/exercises/macros/macros3.rs b/exercises/macros/macros3.rs
index 93a43113..17cb8e3f 100644
--- a/exercises/macros/macros3.rs
+++ b/exercises/macros/macros3.rs
@@ -4,6 +4,7 @@
 
 // I AM NOT DONE
 
+#[macro_use]
 mod macros {
     macro_rules! my_macro {
         () => {
diff --git a/exercises/macros/macros4.rs b/exercises/macros/macros4.rs
index 3a748078..1b550f43 100644
--- a/exercises/macros/macros4.rs
+++ b/exercises/macros/macros4.rs
@@ -6,10 +6,10 @@
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
-    }
+    };
     ($val:expr) => {
         println!("Look at this other macro: {}", $val);
-    }
+    };
 }
 
 fn main() {
diff --git a/exercises/modules/modules1.rs b/exercises/modules/modules1.rs
index 1a2bd0dd..f74b4b1e 100644
--- a/exercises/modules/modules1.rs
+++ b/exercises/modules/modules1.rs
@@ -9,7 +9,7 @@ mod sausage_factory {
         String::from("Ginger")
     }
 
-    fn make_sausage() {
+    pub fn make_sausage() {
         get_secret_recipe();
         println!("sausage!");
     }
diff --git a/exercises/modules/modules2.rs b/exercises/modules/modules2.rs
index 87f0c458..7b286719 100644
--- a/exercises/modules/modules2.rs
+++ b/exercises/modules/modules2.rs
@@ -8,8 +8,8 @@
 mod delicious_snacks {
 
     // TODO: Fix these use statements
-    use self::fruits::PEAR as ???
-    use self::veggies::CUCUMBER as ???
+    pub use self::fruits::PEAR as fruit;
+    pub use self::veggies::CUCUMBER as veggie;
 
     mod fruits {
         pub const PEAR: &'static str = "Pear";
diff --git a/exercises/modules/modules3.rs b/exercises/modules/modules3.rs
index 8eed77df..96ebf65e 100644
--- a/exercises/modules/modules3.rs
+++ b/exercises/modules/modules3.rs
@@ -8,7 +8,7 @@
 // I AM NOT DONE
 
 // TODO: Complete this use statement
-use ???
+use std::time::{ SystemTime, UNIX_EPOCH };
 
 fn main() {
     match SystemTime::now().duration_since(UNIX_EPOCH) {
diff --git a/exercises/move_semantics/move_semantics1.rs b/exercises/move_semantics/move_semantics1.rs
index e2f5876d..acec55a6 100644
--- a/exercises/move_semantics/move_semantics1.rs
+++ b/exercises/move_semantics/move_semantics1.rs
@@ -4,9 +4,9 @@
 // I AM NOT DONE
 
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
-    let vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(vec0);
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -15,8 +15,7 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics2.rs b/exercises/move_semantics/move_semantics2.rs
index bd21fbb7..48587254 100644
--- a/exercises/move_semantics/move_semantics2.rs
+++ b/exercises/move_semantics/move_semantics2.rs
@@ -7,7 +7,7 @@
 fn main() {
     let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec(&vec0);
 
     // Do not change the following line!
     println!("{} has length {} content `{:?}`", "vec0", vec0.len(), vec0);
@@ -17,8 +17,8 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
-    let mut vec = vec;
+fn fill_vec(vec: &Vec<i32>) -> Vec<i32> {
+    let mut vec = vec.clone();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics3.rs b/exercises/move_semantics/move_semantics3.rs
index 43fef74f..f611b329 100644
--- a/exercises/move_semantics/move_semantics3.rs
+++ b/exercises/move_semantics/move_semantics3.rs
@@ -6,7 +6,7 @@
 // I AM NOT DONE
 
 fn main() {
-    let vec0 = Vec::new();
+    let mut vec0 = Vec::new();
 
     let mut vec1 = fill_vec(vec0);
 
@@ -17,7 +17,7 @@ fn main() {
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 }
 
-fn fill_vec(vec: Vec<i32>) -> Vec<i32> {
+fn fill_vec(mut vec: Vec<i32>) -> Vec<i32> {
     vec.push(22);
     vec.push(44);
     vec.push(66);
diff --git a/exercises/move_semantics/move_semantics4.rs b/exercises/move_semantics/move_semantics4.rs
index 2a23c710..6be3c468 100644
--- a/exercises/move_semantics/move_semantics4.rs
+++ b/exercises/move_semantics/move_semantics4.rs
@@ -7,9 +7,8 @@
 // I AM NOT DONE
 
 fn main() {
-    let vec0 = Vec::new();
 
-    let mut vec1 = fill_vec(vec0);
+    let mut vec1 = fill_vec();
 
     println!("{} has length {} content `{:?}`", "vec1", vec1.len(), vec1);
 
@@ -20,7 +19,7 @@ fn main() {
 
 // `fill_vec()` no longer takes `vec: Vec<i32>` as argument
 fn fill_vec() -> Vec<i32> {
-    let mut vec = vec;
+    let mut vec = Vec::new();
 
     vec.push(22);
     vec.push(44);
diff --git a/exercises/move_semantics/move_semantics5.rs b/exercises/move_semantics/move_semantics5.rs
index 1afe16c5..5f6b1e19 100644
--- a/exercises/move_semantics/move_semantics5.rs
+++ b/exercises/move_semantics/move_semantics5.rs
@@ -8,8 +8,8 @@
 fn main() {
     let mut x = 100;
     let y = &mut x;
-    let z = &mut x;
     *y += 100;
+    let z = &mut x;
     *z += 1000;
     assert_eq!(x, 1200);
 }
diff --git a/exercises/option/option1.rs b/exercises/option/option1.rs
index 602ff1a9..85e8b630 100644
--- a/exercises/option/option1.rs
+++ b/exercises/option/option1.rs
@@ -9,15 +9,15 @@ fn print_number(maybe_number: Option<u16>) {
 }
 
 fn main() {
-    print_number(13);
-    print_number(99);
+    print_number(Some(13));
+    print_number(Some(99));
 
-    let mut numbers: [Option<u16>; 5];
+    let mut numbers: [Option<u16>; 5] = [None; 5];
     for iter in 0..5 {
         let number_to_add: u16 = {
             ((iter * 1235) + 2) / (4 * 16)
         };
 
-        numbers[iter as usize] = number_to_add;
+        numbers[iter as usize] = Some(number_to_add);
     }
 }
diff --git a/exercises/option/option2.rs b/exercises/option/option2.rs
index c6b83ece..1592072d 100644
--- a/exercises/option/option2.rs
+++ b/exercises/option/option2.rs
@@ -6,7 +6,7 @@
 fn main() {
     let optional_word = Some(String::from("rustlings"));
     // TODO: Make this an if let statement whose value is "Some" type
-    word = optional_word {
+    if let Some(word) = optional_word {
         println!("The word is: {}", word);
     } else {
         println!("The optional word doesn't contain anything");
@@ -19,7 +19,7 @@ fn main() {
 
     // TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T>
     // You can stack `Option<T>`'s into while let and if let
-    integer = optional_integers_vec.pop() {
+    while let Some(Some(integer)) = optional_integers_vec.pop() {
         println!("current value: {}", integer);
     }
 }
diff --git a/exercises/option/option3.rs b/exercises/option/option3.rs
index 045d2acb..c37ce534 100644
--- a/exercises/option/option3.rs
+++ b/exercises/option/option3.rs
@@ -11,9 +11,14 @@ struct Point {
 fn main() {
     let y: Option<Point> = Some(Point { x: 100, y: 200 });
 
-    match y {
+    match y.as_ref() {
         Some(p) => println!("Co-ordinates are {},{} ", p.x, p.y),
         _ => println!("no match"),
     }
+
+    match y {
+        Some(ref p) => println!("Co-ordinates are {},{} ", p.x, p.y),
+        _ => println!("no match"),
+    }
     y; // Fix without deleting this line.
 }
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 09121392..ad229e31 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -12,7 +12,7 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = true; // Finish the rest of this line like the example! Or make it be false!
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index 6576a4d5..ceb0cd31 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -1,4 +1,3 @@
-// primitive_types2.rs
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
@@ -16,7 +15,7 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = '😊'; // Finish this line like the example! What's your favorite character?
     // Try a letter, try a number, try a special character, try a character
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index aaa518be..ea56b7ae 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -5,7 +5,7 @@
 // I AM NOT DONE
 
 fn main() {
-    let a = ???
+    let a = [1; 100];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");
diff --git a/exercises/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index 10b553e9..f62477a3 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -8,7 +8,7 @@
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }
diff --git a/exercises/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index 680d8d23..9c9105eb 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -6,7 +6,7 @@
 
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    let (name, age) = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index b8c9b82b..b0034372 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -9,7 +9,7 @@
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    let second = numbers.1;
 
     assert_eq!(2, second,
         "This is not the 2nd number in the tuple!")
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index b13b9284..8822ed1a 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -12,6 +12,14 @@
 // Put your function here!
 // fn calculate_apple_price {
 
+fn calculate_apple_price(quantity: usize) -> usize {
+    if quantity <= 40 {
+        quantity * 2
+    } else {
+        quantity * 1
+    }
+}
+
 // Don't modify this function!
 #[test]
 fn verify_test() {
diff --git a/exercises/quiz2.rs b/exercises/quiz2.rs
index de0dce95..d6acee2d 100644
--- a/exercises/quiz2.rs
+++ b/exercises/quiz2.rs
@@ -17,14 +17,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
-    ???("red".to_string());
-    ???(String::from("hi"));
-    ???("rust is fun!".to_owned());
-    ???("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }
diff --git a/exercises/quiz3.rs b/exercises/quiz3.rs
index fae0eedb..ada1ee65 100644
--- a/exercises/quiz3.rs
+++ b/exercises/quiz3.rs
@@ -19,12 +19,12 @@ mod tests {
 
     #[test]
     fn returns_twice_of_positive_numbers() {
-        assert_eq!(times_two(4), ???);
+        assert_eq!(times_two(4), 8);
     }
 
     #[test]
     fn returns_twice_of_negative_numbers() {
         // TODO replace unimplemented!() with an assert for `times_two(-4)`
-        unimplemented!()
+        assert_eq!(times_two(-4), -8);
     }
 }
diff --git a/exercises/quiz4.rs b/exercises/quiz4.rs
index 6c47480d..f67bf699 100644
--- a/exercises/quiz4.rs
+++ b/exercises/quiz4.rs
@@ -6,6 +6,11 @@
 // Write a macro that passes the quiz! No hints this time, you can do it!
 
 // I AM NOT DONE
+macro_rules! my_macro {
+    ($val:expr) => {
+        format!("Hello {}", $val)
+    };
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/exercises/standard_library_types/arc1.rs b/exercises/standard_library_types/arc1.rs
index d167380c..21714330 100644
--- a/exercises/standard_library_types/arc1.rs
+++ b/exercises/standard_library_types/arc1.rs
@@ -23,17 +23,19 @@
 #![forbid(unused_imports)] // Do not change this, (or the next) line.
 use std::sync::Arc;
 use std::thread;
+use std::sync::Mutex;
 
 fn main() {
     let numbers: Vec<_> = (0..100u32).collect();
-    let shared_numbers = // TODO
+    let shared_numbers = Arc::new(Mutex::new(numbers)); // TODO
     let mut joinhandles = Vec::new();
 
     for offset in 0..8 {
-        let child_numbers = // TODO
+        let child_numbers = Arc::clone(&shared_numbers); // TODO
         joinhandles.push(thread::spawn(move || {
             let mut i = offset;
             let mut sum = 0;
+            let child_numbers = child_numbers.lock().unwrap();
             while i < child_numbers.len() {
                 sum += child_numbers[i];
                 i += 8;
diff --git a/exercises/standard_library_types/box1.rs b/exercises/standard_library_types/box1.rs
index f312f3d6..32af08e1 100644
--- a/exercises/standard_library_types/box1.rs
+++ b/exercises/standard_library_types/box1.rs
@@ -20,7 +20,7 @@
 
 #[derive(PartialEq, Debug)]
 pub enum List {
-    Cons(i32, List),
+    Cons(i32, Box<List>),
     Nil,
 }
 
@@ -33,11 +33,11 @@ fn main() {
 }
 
 pub fn create_empty_list() -> List {
-    unimplemented!()
+    List::Nil
 }
 
 pub fn create_non_empty_list() -> List {
-    unimplemented!()
+    List::Cons(0, Box::new(List::Nil))
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators1.rs b/exercises/standard_library_types/iterators1.rs
index 4606ad35..1ec25132 100644
--- a/exercises/standard_library_types/iterators1.rs
+++ b/exercises/standard_library_types/iterators1.rs
@@ -13,12 +13,12 @@
 fn main () {
     let my_fav_fruits = vec!["banana", "custard apple", "avocado", "peach", "raspberry"];
 
-    let mut my_iterable_fav_fruits = ???;   // TODO: Step 1
+    let mut my_iterable_fav_fruits = my_fav_fruits.iter();   // TODO: Step 1
 
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"banana"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"custard apple"));     // TODO: Step 2
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"avocado"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 2.1
+    assert_eq!(my_iterable_fav_fruits.next(), Some(&"peach"));     // TODO: Step 2.1
     assert_eq!(my_iterable_fav_fruits.next(), Some(&"raspberry"));
-    assert_eq!(my_iterable_fav_fruits.next(), ???);     // TODO: Step 3
+    assert_eq!(my_iterable_fav_fruits.next(), None);     // TODO: Step 3
 }
diff --git a/exercises/standard_library_types/iterators2.rs b/exercises/standard_library_types/iterators2.rs
index 87b4eaa1..a823eee7 100644
--- a/exercises/standard_library_types/iterators2.rs
+++ b/exercises/standard_library_types/iterators2.rs
@@ -12,7 +12,11 @@ pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => ???,
+        Some(first) => {
+            let mut s = first.to_string().to_uppercase();
+            s.push_str(&input[1..]);
+            s
+        },
     }
 }
 
@@ -21,7 +25,11 @@ pub fn capitalize_first(input: &str) -> String {
 // Return a vector of strings.
 // ["hello", "world"] -> ["Hello", "World"]
 pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
-    vec![]
+    let mut v = Vec::new();
+    for word in words {
+        v.push(capitalize_first(word));
+    }
+    v
 }
 
 // Step 3.
@@ -29,7 +37,8 @@ pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
 // Return a single string.
 // ["hello", " ", "world"] -> "Hello World"
 pub fn capitalize_words_string(words: &[&str]) -> String {
-    String::new()
+    let v = capitalize_words_vector(words);
+    v.join("")
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators3.rs b/exercises/standard_library_types/iterators3.rs
index 8c66c05b..8192c2c8 100644
--- a/exercises/standard_library_types/iterators3.rs
+++ b/exercises/standard_library_types/iterators3.rs
@@ -22,20 +22,34 @@ pub struct NotDivisibleError {
 
 // Calculate `a` divided by `b` if `a` is evenly divisible by `b`.
 // Otherwise, return a suitable error.
-pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {}
+pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
+    if b == 0 {
+        Err(DivisionError::DivideByZero)
+    } else {
+        if a % b == 0 {
+            Ok(a / b)
+        } else {
+            Err(DivisionError::NotDivisible(
+                NotDivisibleError{dividend: a, divisor: b}
+            ))
+        }
+    }
+}
 
 // Complete the function and return a value of the correct type so the test passes.
 // Desired output: Ok([1, 11, 1426, 3])
-fn result_with_list() -> () {
+fn result_with_list() -> Result<Vec<i32>, DivisionError> {
     let numbers = vec![27, 297, 38502, 81];
-    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    let division_results = numbers.into_iter().map(|n| divide(n, 27).unwrap()).collect();
+    Ok(division_results)
 }
 
 // Complete the function and return a value of the correct type so the test passes.
 // Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
-fn list_of_results() -> () {
+fn list_of_results() -> Vec<Result<i32, DivisionError>> {
     let numbers = vec![27, 297, 38502, 81];
-    let division_results = numbers.into_iter().map(|n| divide(n, 27));
+    let division_results = numbers.into_iter().map(|n| divide(n, 27)).collect();
+    division_results
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators4.rs b/exercises/standard_library_types/iterators4.rs
index 88862838..6379bbe7 100644
--- a/exercises/standard_library_types/iterators4.rs
+++ b/exercises/standard_library_types/iterators4.rs
@@ -12,6 +12,11 @@ pub fn factorial(num: u64) -> u64 {
     // For an extra challenge, don't use:
     // - recursion
     // Execute `rustlings hint iterators4` for hints.
+    let mut res = 1;
+    for i in 1..num+1 {
+        res *= i;
+    }
+    res
 }
 
 #[cfg(test)]
diff --git a/exercises/standard_library_types/iterators5.rs b/exercises/standard_library_types/iterators5.rs
index 93f3ae11..6adb1b80 100644
--- a/exercises/standard_library_types/iterators5.rs
+++ b/exercises/standard_library_types/iterators5.rs
@@ -34,6 +34,13 @@ fn count_for(map: &HashMap<String, Progress>, value: Progress) -> usize {
 fn count_iterator(map: &HashMap<String, Progress>, value: Progress) -> usize {
     // map is a hashmap with String keys and Progress values.
     // map = { "variables1": Complete, "from_str": None, ... }
+    let mut count = 0;
+    for (_, val) in map.iter() {
+        if val == &value { 
+            count += 1;
+        }
+    }
+    count
 }
 
 fn count_collection_for(collection: &[HashMap<String, Progress>], value: Progress) -> usize {
@@ -52,6 +59,15 @@ fn count_collection_iterator(collection: &[HashMap<String, Progress>], value: Pr
     // collection is a slice of hashmaps.
     // collection = [{ "variables1": Complete, "from_str": None, ... },
     //     { "variables2": Complete, ... }, ... ]
+    let mut count = 0;
+    for map in collection.iter() {
+        for (_, val) in map.iter() {
+            if val == &value {
+                count += 1;
+            }
+        } 
+    }
+    count
 }
 
 #[cfg(test)]
diff --git a/exercises/strings/strings1.rs b/exercises/strings/strings1.rs
index 80902444..5df9ba25 100644
--- a/exercises/strings/strings1.rs
+++ b/exercises/strings/strings1.rs
@@ -10,5 +10,5 @@ fn main() {
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }
diff --git a/exercises/strings/strings2.rs b/exercises/strings/strings2.rs
index 5a2ce74a..1d7c0395 100644
--- a/exercises/strings/strings2.rs
+++ b/exercises/strings/strings2.rs
@@ -6,7 +6,7 @@
 
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word[..]) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");
diff --git a/exercises/structs/structs1.rs b/exercises/structs/structs1.rs
index 6d0b2f49..3a22eaae 100644
--- a/exercises/structs/structs1.rs
+++ b/exercises/structs/structs1.rs
@@ -3,11 +3,12 @@
 
 // I AM NOT DONE
 
-struct ColorClassicStruct {
-    // TODO: Something goes here
+struct ColorClassicStruct<'a> {
+    name: &'a str,
+    hex: &'a str
 }
 
-struct ColorTupleStruct(/* TODO: Something goes here */);
+struct ColorTupleStruct<'a>(&'a str, &'a str);
 
 #[derive(Debug)]
 struct UnitStruct;
@@ -19,7 +20,7 @@ mod tests {
     #[test]
     fn classic_c_structs() {
         // TODO: Instantiate a classic c struct!
-        // let green =
+        let green = ColorClassicStruct { name: "green", hex: "#00FF00" };
 
         assert_eq!(green.name, "green");
         assert_eq!(green.hex, "#00FF00");
@@ -28,7 +29,7 @@ mod tests {
     #[test]
     fn tuple_structs() {
         // TODO: Instantiate a tuple struct!
-        // let green =
+        let green = ColorTupleStruct ( "green", "#00FF00" );
 
         assert_eq!(green.0, "green");
         assert_eq!(green.1, "#00FF00");
@@ -36,8 +37,8 @@ mod tests {
 
     #[test]
     fn unit_structs() {
-        // TODO: Instantiate a unit struct!
-        // let unit_struct =
+        // TODO: Instantiate a unit struct
+        let unit_struct = UnitStruct;
         let message = format!("{:?}s are fun!", unit_struct);
 
         assert_eq!(message, "UnitStructs are fun!");
diff --git a/exercises/structs/structs2.rs b/exercises/structs/structs2.rs
index f9c6427d..113e6152 100644
--- a/exercises/structs/structs2.rs
+++ b/exercises/structs/structs2.rs
@@ -34,7 +34,15 @@ mod tests {
     fn your_order() {
         let order_template = create_order_template();
         // TODO: Create your own order using the update syntax and template above!
-        // let your_order =
+        let your_order = Order {
+            name: String::from("Hacker in Rust"),
+            year: 2019,
+            made_by_phone: false,
+            made_by_mobile: false,
+            made_by_email: true,
+            item_number: 123,
+            count: 1,
+        };
         assert_eq!(your_order.name, "Hacker in Rust");
         assert_eq!(your_order.year, order_template.year);
         assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
diff --git a/exercises/structs/structs3.rs b/exercises/structs/structs3.rs
index a80d0625..5e3c4854 100644
--- a/exercises/structs/structs3.rs
+++ b/exercises/structs/structs3.rs
@@ -17,6 +17,7 @@ impl Package {
     fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
         if weight_in_grams <= 0 {
             // Something goes here...
+            panic!("Weight of package is less than 0.");
         } else {
             return Package {
                 sender_country,
@@ -26,12 +27,12 @@ impl Package {
         }
     }
 
-    fn is_international(&self) -> ??? {
-        // Something goes here...
+    fn is_international(&self) -> bool {
+        self.sender_country != self.recipient_country
     }
 
-    fn get_fees(&self, cents_per_gram: i32) -> ??? {
-        // Something goes here...
+    fn get_fees(&self, cents_per_gram: i32) -> i32 {
+        self.weight_in_grams * cents_per_gram
     }
 }
 
@@ -73,7 +74,7 @@ mod tests {
         let sender_country = String::from("Spain");
         let recipient_country = String::from("Spain");
 
-        let cents_per_gram = ???;
+        let cents_per_gram = 3;
 
         let package = Package::new(sender_country, recipient_country, 1500);
 
diff --git a/exercises/tests/tests1.rs b/exercises/tests/tests1.rs
index 50586a19..7ba6363d 100644
--- a/exercises/tests/tests1.rs
+++ b/exercises/tests/tests1.rs
@@ -12,6 +12,6 @@
 mod tests {
     #[test]
     fn you_can_assert() {
-        assert!();
+        assert!(true);
     }
 }
diff --git a/exercises/tests/tests2.rs b/exercises/tests/tests2.rs
index 0d981ad1..2e19a0b5 100644
--- a/exercises/tests/tests2.rs
+++ b/exercises/tests/tests2.rs
@@ -8,6 +8,6 @@
 mod tests {
     #[test]
     fn you_can_assert_eq() {
-        assert_eq!();
+        assert_eq!(1, 1);
     }
 }
diff --git a/exercises/tests/tests3.rs b/exercises/tests/tests3.rs
index 3424f940..11c7dfd2 100644
--- a/exercises/tests/tests3.rs
+++ b/exercises/tests/tests3.rs
@@ -16,11 +16,11 @@ mod tests {
 
     #[test]
     fn is_true_when_even() {
-        assert!();
+        assert!(is_even(2));
     }
 
     #[test]
     fn is_false_when_odd() {
-        assert!();
+        assert!(!is_even(1));
     }
 }
diff --git a/exercises/threads/threads1.rs b/exercises/threads/threads1.rs
index f31b317e..2ca1e453 100644
--- a/exercises/threads/threads1.rs
+++ b/exercises/threads/threads1.rs
@@ -9,6 +9,7 @@
 // I AM NOT DONE
 
 use std::sync::Arc;
+use std::sync::Mutex;
 use std::thread;
 use std::time::Duration;
 
@@ -17,15 +18,15 @@ struct JobStatus {
 }
 
 fn main() {
-    let status = Arc::new(JobStatus { jobs_completed: 0 });
+    let status = Arc::new(Mutex::new( JobStatus { jobs_completed: 0 }));
     let status_shared = status.clone();
     thread::spawn(move || {
         for _ in 0..10 {
             thread::sleep(Duration::from_millis(250));
-            status_shared.jobs_completed += 1;
+            status_shared.lock().unwrap().jobs_completed += 1;
         }
     });
-    while status.jobs_completed < 10 {
+    while status.lock().unwrap().jobs_completed < 10 {
         println!("waiting... ");
         thread::sleep(Duration::from_millis(500));
     }
diff --git a/exercises/traits/traits1.rs b/exercises/traits/traits1.rs
index 2ef9e11b..b96e837a 100644
--- a/exercises/traits/traits1.rs
+++ b/exercises/traits/traits1.rs
@@ -16,6 +16,11 @@ trait AppendBar {
 
 impl AppendBar for String {
     //Add your code here
+    fn append_bar(self) -> Self {
+        let mut s = self.clone();
+        s.push_str("Bar");
+        s
+    }
 }
 
 fn main() {
diff --git a/exercises/traits/traits2.rs b/exercises/traits/traits2.rs
index 916c3c4b..1864e726 100644
--- a/exercises/traits/traits2.rs
+++ b/exercises/traits/traits2.rs
@@ -17,6 +17,13 @@ trait AppendBar {
 }
 
 //TODO: Add your code here
+impl AppendBar for Vec<String> {
+    fn append_bar(self) -> Self {
+        let mut v = self.clone();
+        v.push("Bar".to_string());
+        return v;
+    }
+}
 
 #[cfg(test)]
 mod tests {
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index 4a3af73c..8734065c 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -9,6 +9,6 @@
 // I AM NOT DONE
 
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }
diff --git a/exercises/variables/variables2.rs b/exercises/variables/variables2.rs
index 7774a8fb..ced90b88 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -4,7 +4,7 @@
 // I AM NOT DONE
 
 fn main() {
-    let x;
+    let x = 10;
     if x == 10 {
         println!("Ten!");
     } else {
diff --git a/exercises/variables/variables3.rs b/exercises/variables/variables3.rs
index 30ec48ff..1f13bdad 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -4,7 +4,7 @@
 // I AM NOT DONE
 
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);
diff --git a/exercises/variables/variables4.rs b/exercises/variables/variables4.rs
index 77f1e9ab..b6e92741 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -4,6 +4,6 @@
 // I AM NOT DONE
 
 fn main() {
-    let x: i32;
+    let x: i32 = 10;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables5.rs b/exercises/variables/variables5.rs
index 175eebb3..cd9846aa 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -6,6 +6,6 @@
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3;
+    let number = 3;
     println!("Number plus two is : {}", number + 2);
 }
diff --git a/exercises/variables/variables6.rs b/exercises/variables/variables6.rs
index 98666914..6afe3542 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -3,7 +3,7 @@
 
 // I AM NOT DONE
 
-const NUMBER = 3;
+const NUMBER: i8 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }