diff --git a/error_handling/errors1.rs b/error_handling/errors1.rs
index 843e620..14ed574 100644
--- a/error_handling/errors1.rs
+++ b/error_handling/errors1.rs
@@ -1,3 +1,4 @@
+// errors1.rs
 // This function refuses to generate text to be printed on a nametag if
 // you pass it an empty string. It'd be nicer if it explained what the problem
 // was, instead of just sometimes returning `None`. The 2nd test currently
diff --git a/error_handling/errors2.rs b/error_handling/errors2.rs
index a9cb940..05824c1 100644
--- a/error_handling/errors2.rs
+++ b/error_handling/errors2.rs
@@ -1,3 +1,4 @@
+// errors2.rs
 // Say we're writing a game where you can buy items with tokens. All items cost
 // 5 tokens, and whenever you purchase items there is a processing fee of 1
 // token. A player of the game will type in how many items they want to buy,
diff --git a/error_handling/errors3.rs b/error_handling/errors3.rs
index 3ecffbc..9b285e0 100644
--- a/error_handling/errors3.rs
+++ b/error_handling/errors3.rs
@@ -1,3 +1,4 @@
+// errors3.rs
 // This is a program that is trying to use a completed version of the
 // `total_cost` function from the previous exercise. It's not working though--
 // we can't call the `try!` macro in the `main()` function! Why not?
diff --git a/error_handling/errorsn.rs b/error_handling/errorsn.rs
index e0d73da..4fb2be3 100644
--- a/error_handling/errorsn.rs
+++ b/error_handling/errorsn.rs
@@ -1,3 +1,4 @@
+// errorsn.rs
 // This is a bigger error exercise than the previous ones!
 // You can do it!
 //
diff --git a/error_handling/option1.rs b/error_handling/option1.rs
index 5f96184..9cf0bc9 100644
--- a/error_handling/option1.rs
+++ b/error_handling/option1.rs
@@ -1,3 +1,4 @@
+// option1.rs
 // This example panics because the second time it calls `pop`, the `vec`
 // is empty, so `pop` returns `None`, and `unwrap` panics if it's called
 // on `None`. Handle this in a more graceful way than calling `unwrap`!
diff --git a/error_handling/result1.rs b/error_handling/result1.rs
index 7146d1e..851ab45 100644
--- a/error_handling/result1.rs
+++ b/error_handling/result1.rs
@@ -1,3 +1,4 @@
+// result1.rs
 // Make this test pass! Scroll down for hints :)
 
 #[derive(PartialEq,Debug)]
diff --git a/ex1.rs b/ex1.rs
index b619495..2366991 100644
--- a/ex1.rs
+++ b/ex1.rs
@@ -1,3 +1,4 @@
+// ex1.rs
 // Make me compile!
 
 fn main() {
diff --git a/ex2.rs b/ex2.rs
index b0c7ca2..0fd714d 100644
--- a/ex2.rs
+++ b/ex2.rs
@@ -1,3 +1,4 @@
+// ex2.rs
 // Make me compile!
 
 fn something() -> String {
diff --git a/ex3.rs b/ex3.rs
index 242076f..db27ad2 100644
--- a/ex3.rs
+++ b/ex3.rs
@@ -1,3 +1,4 @@
+// ex3.rs
 // Make me compile!
 
 struct Foo {
diff --git a/ex4.rs b/ex4.rs
index d1ae563..362a557 100644
--- a/ex4.rs
+++ b/ex4.rs
@@ -1,3 +1,4 @@
+// ex4.rs
 // Make me compile!
 
 fn something() -> Result<i32, std::num::ParseIntError> {
diff --git a/ex5.rs b/ex5.rs
index 661b15e..2eb8cfd 100644
--- a/ex5.rs
+++ b/ex5.rs
@@ -1,3 +1,4 @@
+// ex5.rs
 // Make me compile!
 
 enum Reaction<'a> {
diff --git a/functions/functions1.rs b/functions/functions1.rs
index 3004363..396dd56 100644
--- a/functions/functions1.rs
+++ b/functions/functions1.rs
@@ -1,3 +1,4 @@
+// functions1.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/functions/functions2.rs b/functions/functions2.rs
index 97ed8f1..1cf95c3 100644
--- a/functions/functions2.rs
+++ b/functions/functions2.rs
@@ -1,3 +1,4 @@
+// functions2.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/functions/functions3.rs b/functions/functions3.rs
index 3dba67c..b17543b 100644
--- a/functions/functions3.rs
+++ b/functions/functions3.rs
@@ -1,3 +1,4 @@
+// functions3.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/functions/functions4.rs b/functions/functions4.rs
index e514b84..4da8d70 100644
--- a/functions/functions4.rs
+++ b/functions/functions4.rs
@@ -1,3 +1,4 @@
+// functions4.rs
 // Make me compile! Scroll down for hints :)
 
 // This store is having a sale where if the price is an even number, you get
diff --git a/functions/functions5.rs b/functions/functions5.rs
index a8d7cef..f8fac5d 100644
--- a/functions/functions5.rs
+++ b/functions/functions5.rs
@@ -1,3 +1,4 @@
+// functions5.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/if/if1.rs b/if/if1.rs
index c2ea734..5118657 100644
--- a/if/if1.rs
+++ b/if/if1.rs
@@ -1,3 +1,5 @@
+// if1.rs
+
 pub fn bigger(a: i32, b:i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
diff --git a/macros/macros1.rs b/macros/macros1.rs
index 0e964ac..a7c78a5 100644
--- a/macros/macros1.rs
+++ b/macros/macros1.rs
@@ -1,3 +1,4 @@
+// macros1.rs
 // Make me compile! Scroll down for hints :)
 
 macro_rules! my_macro {
diff --git a/macros/macros2.rs b/macros/macros2.rs
index bd5a82c..bc2e56b 100644
--- a/macros/macros2.rs
+++ b/macros/macros2.rs
@@ -1,3 +1,4 @@
+// macros2.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/macros/macros3.rs b/macros/macros3.rs
index 8281445..84c4308 100644
--- a/macros/macros3.rs
+++ b/macros/macros3.rs
@@ -1,3 +1,4 @@
+// macros3.rs
 // Make me compile, without taking the macro out of the module! Scroll down for hints :)
 
 mod macros {
diff --git a/macros/macros4.rs b/macros/macros4.rs
index a15e171..d844bb0 100644
--- a/macros/macros4.rs
+++ b/macros/macros4.rs
@@ -1,3 +1,4 @@
+// macros4.rs
 // Make me compile! Scroll down for hints :)
 
 macro_rules! my_macro {
diff --git a/modules/modules1.rs b/modules/modules1.rs
index 7163495..0e092c5 100644
--- a/modules/modules1.rs
+++ b/modules/modules1.rs
@@ -1,3 +1,4 @@
+// modules1.rs
 // Make me compile! Scroll down for hints :)
 
 mod sausage_factory {
diff --git a/modules/modules2.rs b/modules/modules2.rs
index e6d6f4c..fefca90 100644
--- a/modules/modules2.rs
+++ b/modules/modules2.rs
@@ -1,3 +1,4 @@
+// modules2.rs
 // Make me compile! Scroll down for hints :)
 
 mod us_presidential_frontrunners {
diff --git a/move_semantics/move_semantics1.rs b/move_semantics/move_semantics1.rs
index a69ff90..1f28873 100644
--- a/move_semantics/move_semantics1.rs
+++ b/move_semantics/move_semantics1.rs
@@ -1,3 +1,4 @@
+// move_semantics1.rs
 // Make me compile! Scroll down for hints :)
 
 pub fn main() {
diff --git a/move_semantics/move_semantics2.rs b/move_semantics/move_semantics2.rs
index 79c1c56..6e676d1 100644
--- a/move_semantics/move_semantics2.rs
+++ b/move_semantics/move_semantics2.rs
@@ -1,3 +1,4 @@
+// move_semantics2.rs
 // Make me compile without changing line 9! Scroll down for hints :)
 
 pub fn main() {
diff --git a/move_semantics/move_semantics3.rs b/move_semantics/move_semantics3.rs
index fec370f..7805d44 100644
--- a/move_semantics/move_semantics3.rs
+++ b/move_semantics/move_semantics3.rs
@@ -1,3 +1,4 @@
+// move_semantics3.rs
 // Make me compile without adding new lines-- just changing existing lines!
 // (no lines with multiple semicolons necessary!)
 // Scroll down for hints :)
diff --git a/move_semantics/move_semantics4.rs b/move_semantics/move_semantics4.rs
index 17df426..2b1ed8a 100644
--- a/move_semantics/move_semantics4.rs
+++ b/move_semantics/move_semantics4.rs
@@ -1,3 +1,4 @@
+// move_semantics4.rs
 // Refactor this code so that instead of having `vec0` and creating the vector
 // in `fn main`, we instead create it within `fn fill_vec` and transfer the
 // freshly created vector from fill_vec to its caller. Scroll for hints!
diff --git a/primitive_types/primitive_types1.rs b/primitive_types/primitive_types1.rs
index 95c06de..c3d11fe 100644
--- a/primitive_types/primitive_types1.rs
+++ b/primitive_types/primitive_types1.rs
@@ -1,3 +1,4 @@
+// primitive_types1.rs
 // Fill in the rest of the line that has code missing!
 // No hints, there's no tricks, just get used to typing these :)
 
diff --git a/primitive_types/primitive_types2.rs b/primitive_types/primitive_types2.rs
index a2c80f5..f5c8f87 100644
--- a/primitive_types/primitive_types2.rs
+++ b/primitive_types/primitive_types2.rs
@@ -1,3 +1,4 @@
+// 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 :)
 
diff --git a/primitive_types/primitive_types3.rs b/primitive_types/primitive_types3.rs
index 3476ba6..a2f9b3b 100644
--- a/primitive_types/primitive_types3.rs
+++ b/primitive_types/primitive_types3.rs
@@ -1,3 +1,4 @@
+// primitive_types3.rs
 // Create an array with at least 100 elements in it where the ??? is. 
 // Scroll down for hints!
 
diff --git a/primitive_types/primitive_types4.rs b/primitive_types/primitive_types4.rs
index b71cc33..c20b63b 100644
--- a/primitive_types/primitive_types4.rs
+++ b/primitive_types/primitive_types4.rs
@@ -1,3 +1,4 @@
+// primitive_types4.rs
 // Get a slice out of Array a where the ??? is so that the `if` statement
 // returns true. Scroll down for hints!!
 
diff --git a/primitive_types/primitive_types5.rs b/primitive_types/primitive_types5.rs
index a34b750..14c2fd2 100644
--- a/primitive_types/primitive_types5.rs
+++ b/primitive_types/primitive_types5.rs
@@ -1,3 +1,4 @@
+// primitive_types5.rs
 // Destructure the `cat` tuple so that the println will work.
 // Scroll down for hints!
 
diff --git a/primitive_types/primitive_types6.rs b/primitive_types/primitive_types6.rs
index 7ff9c67..d016642 100644
--- a/primitive_types/primitive_types6.rs
+++ b/primitive_types/primitive_types6.rs
@@ -1,3 +1,4 @@
+// primitive_types6.rs
 // Use a tuple index to access the second element of `numbers`.
 // You can put this right into the `println!` where the ??? is.
 // Scroll down for hints!
diff --git a/standard_library_types/arc1.rs b/standard_library_types/arc1.rs
index a47dc19..c744a10 100644
--- a/standard_library_types/arc1.rs
+++ b/standard_library_types/arc1.rs
@@ -1,3 +1,4 @@
+// arc1.rs
 // Make this code compile by filling in a value for `shared_numbers` where the
 // TODO comment is and creating an initial binding for `child_numbers`
 // somewhere. Try not to create any copies of the `numbers` Vec!
diff --git a/standard_library_types/iterator3.rs b/standard_library_types/iterator3.rs
index 0e0cb3e..e973ac6 100644
--- a/standard_library_types/iterator3.rs
+++ b/standard_library_types/iterator3.rs
@@ -1,3 +1,4 @@
+// iterator3.rs
 // This is a bigger exercise than most of the others! You can do it!
 // Here is your mission, should you choose to accept it:
 // 1. Complete the divide function to get the first four tests to pass
diff --git a/standard_library_types/iterators4.rs b/standard_library_types/iterators4.rs
index e758bd1..13613a6 100644
--- a/standard_library_types/iterators4.rs
+++ b/standard_library_types/iterators4.rs
@@ -1,3 +1,5 @@
+// iterators4.rs
+
 pub fn factorial(num: u64) -> u64 {
     // Complete this function to return factorial of num
     // Do not use:
diff --git a/strings/strings1.rs b/strings/strings1.rs
index 2bfbba2..2e5088f 100644
--- a/strings/strings1.rs
+++ b/strings/strings1.rs
@@ -1,3 +1,4 @@
+// strings1.rs
 // Make me compile without changing the function signature! Scroll down for hints :)
 
 fn main() {
diff --git a/strings/strings2.rs b/strings/strings2.rs
index 286a4f8..4239ff8 100644
--- a/strings/strings2.rs
+++ b/strings/strings2.rs
@@ -1,3 +1,4 @@
+// strings2.rs
 // Make me compile without changing the function signature! Scroll down for hints :)
 
 fn main() {
diff --git a/strings/strings3.rs b/strings/strings3.rs
index a4e5775..b6f6a1e 100644
--- a/strings/strings3.rs
+++ b/strings/strings3.rs
@@ -1,3 +1,4 @@
+// strings3.rs
 // Ok, here are a bunch of values-- some are `Strings`, some are `&strs`. Your
 // task is to call one of these two functions on each value depending on what
 // you think each value is. That is, add either `string_slice` or `string`
diff --git a/tests/tests1.rs b/tests/tests1.rs
index e189f93..959ed85 100644
--- a/tests/tests1.rs
+++ b/tests/tests1.rs
@@ -1,3 +1,4 @@
+// tests1.rs
 // Tests are important to ensure that your code does what you think it should do.
 // Tests can be run on this file with the following command:
 // rustc --test tests1.rs
diff --git a/tests/tests2.rs b/tests/tests2.rs
index 0ae6ddb..6775d61 100644
--- a/tests/tests2.rs
+++ b/tests/tests2.rs
@@ -1,3 +1,4 @@
+// tests2.rs
 // This test has a problem with it -- make the test compile! Make the test
 // pass! Make the test fail! Scroll down for hints :)
 
diff --git a/tests/tests3.rs b/tests/tests3.rs
index 1ee0f29..e041f38 100644
--- a/tests/tests3.rs
+++ b/tests/tests3.rs
@@ -1,3 +1,4 @@
+// tests3.rs
 // This test isn't testing our function -- make it do that in such a way that
 // the test passes. Then write a second test that tests that we get the result
 // we expect to get when we call `is_even(5)`. Scroll down for hints!
diff --git a/tests/tests4.rs b/tests/tests4.rs
index 278e29e..23d444a 100644
--- a/tests/tests4.rs
+++ b/tests/tests4.rs
@@ -1,3 +1,4 @@
+// tests4.rs
 // This test isn't testing our function -- make it do that in such a way that
 // the test passes. Then write a second test that tests that we get the result
 // we expect to get when we call `times_two` with a negative number.
diff --git a/threads/threads1.rs b/threads/threads1.rs
index af97552..d98db69 100644
--- a/threads/threads1.rs
+++ b/threads/threads1.rs
@@ -1,3 +1,4 @@
+// threads1.rs
 // Make this compile! Scroll down for hints :) The idea is the thread
 // spawned on line 17 is completing jobs while the main thread is
 // monitoring progress until 10 jobs are completed. If you see 6 lines
diff --git a/variables/variables1.rs b/variables/variables1.rs
index e0ad5de..ffd661c 100644
--- a/variables/variables1.rs
+++ b/variables/variables1.rs
@@ -1,3 +1,4 @@
+// variables1.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/variables/variables2.rs b/variables/variables2.rs
index ca02438..348c2d8 100644
--- a/variables/variables2.rs
+++ b/variables/variables2.rs
@@ -1,3 +1,4 @@
+// variables2.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/variables/variables3.rs b/variables/variables3.rs
index ec55a95..165a277 100644
--- a/variables/variables3.rs
+++ b/variables/variables3.rs
@@ -1,3 +1,4 @@
+// variables3.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {
diff --git a/variables/variables4.rs b/variables/variables4.rs
index 3f7f937..20ee64e 100644
--- a/variables/variables4.rs
+++ b/variables/variables4.rs
@@ -1,3 +1,4 @@
+// variables4.rs
 // Make me compile! Scroll down for hints :)
 
 fn main() {