diff --git a/dev/Cargo.toml b/dev/Cargo.toml
index 4f725b704b..2f4c83d3d0 100644
--- a/dev/Cargo.toml
+++ b/dev/Cargo.toml
@@ -72,20 +72,22 @@ bin = [
   { name = "enums2_sol", path = "../solutions/08_enums/enums2.rs" },
   { name = "enums3", path = "../exercises/08_enums/enums3.rs" },
   { name = "enums3_sol", path = "../solutions/08_enums/enums3.rs" },
-  { name = "strings1", path = "../exercises/09_strings/strings1.rs" },
-  { name = "strings1_sol", path = "../solutions/09_strings/strings1.rs" },
-  { name = "strings2", path = "../exercises/09_strings/strings2.rs" },
-  { name = "strings2_sol", path = "../solutions/09_strings/strings2.rs" },
-  { name = "strings3", path = "../exercises/09_strings/strings3.rs" },
-  { name = "strings3_sol", path = "../solutions/09_strings/strings3.rs" },
-  { name = "strings4", path = "../exercises/09_strings/strings4.rs" },
-  { name = "strings4_sol", path = "../solutions/09_strings/strings4.rs" },
-  { name = "modules1", path = "../exercises/10_modules/modules1.rs" },
-  { name = "modules1_sol", path = "../solutions/10_modules/modules1.rs" },
-  { name = "modules2", path = "../exercises/10_modules/modules2.rs" },
-  { name = "modules2_sol", path = "../solutions/10_modules/modules2.rs" },
-  { name = "modules3", path = "../exercises/10_modules/modules3.rs" },
-  { name = "modules3_sol", path = "../solutions/10_modules/modules3.rs" },
+  { name = "strings1", path = "../exercises/10_strings/strings1.rs" },
+  { name = "strings1_sol", path = "../solutions/10_strings/strings1.rs" },
+  { name = "strings2", path = "../exercises/10_strings/strings2.rs" },
+  { name = "strings2_sol", path = "../solutions/10_strings/strings2.rs" },
+  { name = "strings3", path = "../exercises/10_strings/strings3.rs" },
+  { name = "strings3_sol", path = "../solutions/10_strings/strings3.rs" },
+  { name = "strings4", path = "../exercises/10_strings/strings4.rs" },
+  { name = "strings4_sol", path = "../solutions/10_strings/strings4.rs" },
+  { name = "modules1", path = "../exercises/09_modules/modules1.rs" },
+  { name = "modules1_sol", path = "../solutions/09_modules/modules1.rs" },
+  { name = "modules2", path = "../exercises/09_modules/modules2.rs" },
+  { name = "modules2_sol", path = "../solutions/09_modules/modules2.rs" },
+  { name = "modules3", path = "../exercises/09_modules/modules3.rs" },
+  { name = "modules3_sol", path = "../solutions/09_modules/modules3.rs" },
+  { name = "modules4", path = "../exercises/09_modules/modules4.rs" },
+  { name = "modules4_sol", path = "../solutions/09_modules/modules4.rs" },
   { name = "hashmaps1", path = "../exercises/11_hashmaps/hashmaps1.rs" },
   { name = "hashmaps1_sol", path = "../solutions/11_hashmaps/hashmaps1.rs" },
   { name = "hashmaps2", path = "../exercises/11_hashmaps/hashmaps2.rs" },
diff --git a/exercises/10_modules/README.md b/exercises/09_modules/README.md
similarity index 100%
rename from exercises/10_modules/README.md
rename to exercises/09_modules/README.md
diff --git a/exercises/09_modules/fruit.rs b/exercises/09_modules/fruit.rs
new file mode 100644
index 0000000000..dceae23cb0
--- /dev/null
+++ b/exercises/09_modules/fruit.rs
@@ -0,0 +1,3 @@
+pub fn get_fav_fruit() {
+    println("Got your favourite fruit!")
+}
diff --git a/exercises/10_modules/modules1.rs b/exercises/09_modules/modules1.rs
similarity index 100%
rename from exercises/10_modules/modules1.rs
rename to exercises/09_modules/modules1.rs
diff --git a/exercises/10_modules/modules2.rs b/exercises/09_modules/modules2.rs
similarity index 100%
rename from exercises/10_modules/modules2.rs
rename to exercises/09_modules/modules2.rs
diff --git a/exercises/10_modules/modules3.rs b/exercises/09_modules/modules3.rs
similarity index 100%
rename from exercises/10_modules/modules3.rs
rename to exercises/09_modules/modules3.rs
diff --git a/exercises/09_modules/modules4.rs b/exercises/09_modules/modules4.rs
new file mode 100644
index 0000000000..12720e801f
--- /dev/null
+++ b/exercises/09_modules/modules4.rs
@@ -0,0 +1,5 @@
+// TODO: fix the compiler error for missing modules.
+
+fn main() {
+    fruit::get_fav_fruit();
+}
diff --git a/exercises/09_strings/README.md b/exercises/10_strings/README.md
similarity index 100%
rename from exercises/09_strings/README.md
rename to exercises/10_strings/README.md
diff --git a/exercises/09_strings/strings1.rs b/exercises/10_strings/strings1.rs
similarity index 100%
rename from exercises/09_strings/strings1.rs
rename to exercises/10_strings/strings1.rs
diff --git a/exercises/09_strings/strings2.rs b/exercises/10_strings/strings2.rs
similarity index 100%
rename from exercises/09_strings/strings2.rs
rename to exercises/10_strings/strings2.rs
diff --git a/exercises/09_strings/strings3.rs b/exercises/10_strings/strings3.rs
similarity index 100%
rename from exercises/09_strings/strings3.rs
rename to exercises/10_strings/strings3.rs
diff --git a/exercises/09_strings/strings4.rs b/exercises/10_strings/strings4.rs
similarity index 100%
rename from exercises/09_strings/strings4.rs
rename to exercises/10_strings/strings4.rs
diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml
index ca3ecf1f03..261c72f703 100644
--- a/rustlings-macros/info.toml
+++ b/rustlings-macros/info.toml
@@ -457,7 +457,7 @@ to get the variant's values."""
 
 [[exercises]]
 name = "strings1"
-dir = "09_strings"
+dir = "10_strings"
 test = false
 hint = """
 The `current_favorite_color` function is currently returning a string slice
@@ -471,7 +471,7 @@ another way that uses the `From` trait."""
 
 [[exercises]]
 name = "strings2"
-dir = "09_strings"
+dir = "10_strings"
 test = false
 hint = """
 Yes, it would be really easy to fix this by just changing the value bound to
@@ -486,7 +486,7 @@ https://doc.rust-lang.org/book/ch15-02-deref.html#implicit-deref-coercions-with-
 
 [[exercises]]
 name = "strings3"
-dir = "09_strings"
+dir = "10_strings"
 hint = """
 There are many useful standard library functions for strings. Let's try and use
 some of them:
@@ -500,7 +500,7 @@ https://doc.rust-lang.org/std/string/struct.String.html#method.replace"""
 
 [[exercises]]
 name = "strings4"
-dir = "09_strings"
+dir = "10_strings"
 test = false
 hint = """
 Replace `placeholder` with either `string` or `string_slice` in the `main`
@@ -516,7 +516,7 @@ because "blue" is `&str`, not `String`."""
 
 [[exercises]]
 name = "modules1"
-dir = "10_modules"
+dir = "09_modules"
 test = false
 hint = """
 Everything is private in Rust by default. But there's a keyword we can use
@@ -524,7 +524,7 @@ to make something public!"""
 
 [[exercises]]
 name = "modules2"
-dir = "10_modules"
+dir = "09_modules"
 test = false
 hint = """
 The `delicious_snacks` module is trying to present an external interface that
@@ -537,13 +537,25 @@ https://doc.rust-lang.org/book/ch07-04-bringing-paths-into-scope-with-the-use-ke
 
 [[exercises]]
 name = "modules3"
-dir = "10_modules"
+dir = "09_modules"
 test = false
 hint = """
 `UNIX_EPOCH` and `SystemTime` are declared in the `std::time` module. Add a
 `use` statement for these two to bring them into scope. You can use nested
 paths to bring these two in using only one line."""
 
+[[exercises]]
+name = "modules4"
+dir = "09_modules"
+test = false
+hint = """
+The mod.rs is trying to use the modules from the file cake.rs and fruit directory.
+Complete the `mod` statements to fit the use in `main`.
+
+Learn more in The Book:
+https://doc.rust-lang.org/book/ch07-05-separating-modules-into-different-files.html
+"""
+
 # HASHMAPS
 
 [[exercises]]
diff --git a/solutions/09_modules/fruit.rs b/solutions/09_modules/fruit.rs
new file mode 100644
index 0000000000..dceae23cb0
--- /dev/null
+++ b/solutions/09_modules/fruit.rs
@@ -0,0 +1,3 @@
+pub fn get_fav_fruit() {
+    println("Got your favourite fruit!")
+}
diff --git a/solutions/10_modules/modules1.rs b/solutions/09_modules/modules1.rs
similarity index 100%
rename from solutions/10_modules/modules1.rs
rename to solutions/09_modules/modules1.rs
diff --git a/solutions/10_modules/modules2.rs b/solutions/09_modules/modules2.rs
similarity index 100%
rename from solutions/10_modules/modules2.rs
rename to solutions/09_modules/modules2.rs
diff --git a/solutions/10_modules/modules3.rs b/solutions/09_modules/modules3.rs
similarity index 100%
rename from solutions/10_modules/modules3.rs
rename to solutions/09_modules/modules3.rs
diff --git a/solutions/09_modules/modules4.rs b/solutions/09_modules/modules4.rs
new file mode 100644
index 0000000000..b5b77fca17
--- /dev/null
+++ b/solutions/09_modules/modules4.rs
@@ -0,0 +1,5 @@
+mod fruit;
+
+fn main() {
+    fruit::get_fav_fruit();
+}
diff --git a/solutions/09_strings/strings1.rs b/solutions/10_strings/strings1.rs
similarity index 100%
rename from solutions/09_strings/strings1.rs
rename to solutions/10_strings/strings1.rs
diff --git a/solutions/09_strings/strings2.rs b/solutions/10_strings/strings2.rs
similarity index 100%
rename from solutions/09_strings/strings2.rs
rename to solutions/10_strings/strings2.rs
diff --git a/solutions/09_strings/strings3.rs b/solutions/10_strings/strings3.rs
similarity index 100%
rename from solutions/09_strings/strings3.rs
rename to solutions/10_strings/strings3.rs
diff --git a/solutions/09_strings/strings4.rs b/solutions/10_strings/strings4.rs
similarity index 100%
rename from solutions/09_strings/strings4.rs
rename to solutions/10_strings/strings4.rs
diff --git a/src/cargo_toml.rs b/src/cargo_toml.rs
index ce0dfd0cf3..d624f86781 100644
--- a/src/cargo_toml.rs
+++ b/src/cargo_toml.rs
@@ -108,6 +108,7 @@ mod tests {
             ExerciseInfo {
                 name: String::from("1"),
                 dir: None,
+                module_file: None,
                 test: true,
                 strict_clippy: true,
                 hint: String::new(),
@@ -116,6 +117,7 @@ mod tests {
             ExerciseInfo {
                 name: String::from("2"),
                 dir: Some(String::from("d")),
+                module_file: None,
                 test: false,
                 strict_clippy: false,
                 hint: String::new(),
diff --git a/src/info_file.rs b/src/info_file.rs
index 04e5d644a2..b0603dd93a 100644
--- a/src/info_file.rs
+++ b/src/info_file.rs
@@ -11,6 +11,9 @@ pub struct ExerciseInfo {
     pub name: String,
     /// Exercise's directory name inside the `exercises/` directory.
     pub dir: Option<String>,
+    /// Extra one Aditional Module file
+    #[serde(default)]
+    pub module_file: Option<String>,
     /// Run `cargo test` on the exercise.
     #[serde(default = "default_true")]
     pub test: bool,
@@ -52,6 +55,33 @@ impl ExerciseInfo {
 
         path
     }
+
+    pub fn module_file_path(&self) -> Option<String> {
+        if let Some(module_path) = &self.module_file {
+            let mut path = if let Some(dir) = &self.dir {
+                // 14 = 10 + 1 + 3
+                // exercises/ + / + .rs
+                let mut path = String::with_capacity(14 + dir.len() + module_path.len());
+                path.push_str("exercises/");
+                path.push_str(dir);
+                path.push('/');
+                path
+            } else {
+                // 13 = 10 + 3
+                // exercises/ + .rs
+                let mut path = String::with_capacity(13 + module_path.len());
+                path.push_str("exercises/");
+                path
+            };
+
+            path.push_str(&module_path);
+            path.push_str(".rs");
+
+            Some(path)
+        } else {
+            None
+        }
+    }
 }
 
 impl RunnableExercise for ExerciseInfo {