diff --git a/rust/tests/changes_test/src/main.rs b/rust/tests/changes_test/src/main.rs
index cbaa302a0..afe96a1b0 100644
--- a/rust/tests/changes_test/src/main.rs
+++ b/rust/tests/changes_test/src/main.rs
@@ -1,41 +1,54 @@
 /*
-## error types
+## changes
 
 ### Instructions
 
-Make this code compile
+Imagine you are working in a software to control smart lights in a
+house. You have access to an array of all the lights in a house.
 
+Define the associated function `new` to the data structure `Light`
+which creates a new light with the alias passed in the arguments and
+a brightness of 0.
+
+Define the function `change_brightness` that receives a Vec of lights,
+an alias and a u8 value and sets the u8 value as the new brightness of the light
+identified by the alias in the Vec of lights.
 */
 
 use changes::*;
 
 fn main() {
-	let mut a = String::from("Hello");
-
-	println!("the value of `a` before changing {}", a);
-
-	add_excitement(&mut a);
-
-	println!("The value of `a` after changing {}", a);
+	// bedroom
+	let mut lights = vec![
+		Light::new("living_room"),
+		Light::new("bedroom"),
+		Light::new("rest_room"),
+	];
+	println!("brightness = {}", lights[0].brightness);
+	change_brightness(&mut lights, "living_room", 200);
+	println!("new brightness = {}", lights[0].brightness);
 }
 
-// fn add_excitement(s: &mut String) {
-// 	s.push_str("!");
-// }
-
 #[test]
-fn test_ascii() {
-	let mut expected = "hello".to_string();
-	add_excitement(&mut expected);
-	assert_eq!("hello!", &expected);
-	let mut expected = "go on".to_string();
-	add_excitement(&mut expected);
-	assert_eq!("go on!", &expected);
+fn test_unexistente_alias() {
+	let mut lights = Vec::new();
+	for i in 0..5 {
+		let alias = format!("light-{}", i);
+		lights.push(Light::new(&alias));
+	}
+	let copy = lights.clone();
+	change_brightness(&mut lights, "light-6", 100);
+	assert_eq!(copy, lights);
 }
 
 #[test]
-fn test_unicode() {
-	let mut expected = "↕".to_string();
-	add_excitement(&mut expected);
-	assert_eq!(expected, "↕!");
+fn test_alias() {
+	let mut lights = Vec::new();
+	for i in 0..5 {
+		let alias = format!("light-{}", i);
+		lights.push(Light::new(&alias));
+	}
+	let alias = "light-3";
+	change_brightness(&mut lights, alias, 100);
+	assert_eq!(lights[3].brightness, 100);
 }
diff --git a/subjects/changes/README.md b/subjects/changes/README.md
index bedd549ff..f6f096f25 100644
--- a/subjects/changes/README.md
+++ b/subjects/changes/README.md
@@ -2,12 +2,27 @@
 
 ### Instructions
 
-Define the function `add_excitement` that add the exclamation point at the end of every sentenced that is passed to the function without returning anything but just modifying the input.
+Imagine you are working in a software to control smart lights in a house. You have access to an array of all the lights in a house.
 
-### Expected Functions
+Define the associated function `new` to the data structure `Light` which creates a new light with the alias passed in the arguments and a brightness of 0.
+
+Define the function `change_brightness` that receives a Vec of lights, an alias and a u8 value and sets the u8 value as the new brightness of the light identified by the alias in the Vec of lights.
+
+### Expected Functions and Structure
 
 ```rust
-fn add_excitement(s: &) {
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct Light {
+	pub alias: String,
+	pub brightness: u8,
+}
+
+impl Light {
+	pub fn new(alias: &str) -> Self {
+	}
+}
+
+pub fn change_brightness(lights: &mut Vec<Light>, alias: &str, value: u8) {
 }
 ```
 
@@ -17,13 +32,15 @@ Here is an incomplete program to test your function
 
 ```rust
 fn main() {
-	let mut a = String::from("Hello");
-
-	println!("the value of `a` before changing {}", a);
-
-	add_excitement(a);
-
-	println!("The value of `a` after changing {}", a);
+	// bedroom
+	let mut lights = vec![
+		Light::new("living_room"),
+		Light::new("bedroom"),
+		Light::new("rest_room"),
+	];
+	println!("brightness = {}", lights[0].brightness);
+	change_brightness(&mut lights, "living_room", 200);
+	println!("new brightness = {}", lights[0].brightness);
 }
 ```
 
@@ -31,7 +48,7 @@ And its expected output
 
 ```console
 student@ubuntu:~/[[ROOT]]/test$ cargo run
-the value of `a` before changing Hello
-The value of `a` after changing Hello!
+brightness = 0
+new brightness = 200
 student@ubuntu:~/[[ROOT]]/test$
 ```