diff --git a/subjects/borrow_box/README.md b/subjects/borrow_box/README.md
index de0f33cba4..c452202a0b 100644
--- a/subjects/borrow_box/README.md
+++ b/subjects/borrow_box/README.md
@@ -14,7 +14,10 @@ You will implement some **CRUD** functionality for a game session. You will need
 
 - `delete`: which takes ownership of the boxed game session and returns a string: `"game deleted: id -> 0"`, where `0` is the id of the `GameSession`.
 
-> If `nb_games` is 5, then it is "best out of 5", and no more than 5 games can be played. If some player has a score of 3, then the game session is also finished. This is because there is an insufficient number of remaining games for the trailing player to catch up.
+> Examples for `nb_games`:
+>
+> When `nb_games` is 5, the game is best out of 5, and if some player has a score of 3, the game is finished (there aren't enough games for the other player to draw).
+> When `nb_games` is 11, the game is best out of 11, and if some player has a score of 6, the game is finished (there aren't enough games for the other player to draw).
 
 ### Expected Functions
 
diff --git a/subjects/nextprime/README.md b/subjects/nextprime/README.md
index 2eb7e7efaf..d80c8bba1a 100644
--- a/subjects/nextprime/README.md
+++ b/subjects/nextprime/README.md
@@ -6,7 +6,8 @@ Create a **function** which returns the first prime number which is greater than
 
 The function must be optimized, so as to avoid time-outs.
 
-> We consider that only positive numbers can be prime numbers.
+> A prime number is a natural number greater than 1 that is a not a product of two smaller natural numbers.
+> 4 is not a prime number (so it's called a composite number) because it can be represented as 2 \* 2. 5 is a prime number as it can only be represented by 5 \* 1 or 1 \* 5.
 
 ### Expected function
 
diff --git a/subjects/previousprime/README.md b/subjects/previousprime/README.md
index 8cd5c12948..a3a87ba9ea 100644
--- a/subjects/previousprime/README.md
+++ b/subjects/previousprime/README.md
@@ -6,6 +6,9 @@ Create a **function** which returns the first prime number which is less than or
 
 If there are no smaller primes, the function should return `0`.
 
+> A prime number is a natural number greater than 1 that is a not a product of two smaller natural numbers.
+> 4 is not a prime number (so it's called a composite number) because it can be represented as 2 \* 2. 5 is a prime number as it can only be represented by 5 \* 1 or 1 \* 5.
+
 ### Expected function
 
 ```rust
diff --git a/subjects/prime_checker/README.md b/subjects/prime_checker/README.md
index 2389bb3c3c..8a71fe9e40 100644
--- a/subjects/prime_checker/README.md
+++ b/subjects/prime_checker/README.md
@@ -8,6 +8,9 @@ The result will be `None` if the argument is less or equal one, otherwise it wil
 If the `u32` is prime, the function will return an`Ok(u32)`. For any other case it will return an `enum` `PrimeErr`.
 The `enum` `PrimeErr` will be `Even` if the number is a multiple of two or `Divider(u32)` where the `u32` is the smallest divider of the number.
 
+> A prime number is a natural number greater than 1 that is a not a product of two smaller natural numbers.
+> 4 is not a prime number (so it's called a composite number) because it can be represented as 2 \* 2. 5 is a prime number as it can only be represented by 5 \* 1 or 1 \* 5.
+
 > Your solution should be optimized to a certain degree.
 
 ### Expected Function and structure
diff --git a/subjects/scores/README.md b/subjects/scores/README.md
index ff8df267c1..e7d7d5a083 100644
--- a/subjects/scores/README.md
+++ b/subjects/scores/README.md
@@ -2,9 +2,9 @@
 
 ### Instructions
 
-Lets play a little.
+Let's play a little.
 
-Create a function named `score` that given a string, computes the score for that given string as a `u64`.
+Create a function named `score` that given a `&str`, computes the score for that given string as a `u64`.
 
 Each letter has a value, you just have to sum the values of the letters in the given string.
 
@@ -21,6 +21,7 @@ You will need these:
 | Q, Z                         |  10   |
 
 ### Expected functions
+
 > You'll need to work out the function signature for yourself.
 
 ### Usage