diff --git a/src/ui/mod.rs b/src/ui/mod.rs
index f77092d..ba51e35 100644
--- a/src/ui/mod.rs
+++ b/src/ui/mod.rs
@@ -12,6 +12,8 @@ mod setup_test;
 #[cfg(test)]
 mod curriculum_test;
 pub mod systems;
+#[cfg(test)]
+mod systems_test;
 pub mod target;
 
 use bevy::prelude::*;
diff --git a/src/ui/systems_test.rs b/src/ui/systems_test.rs
new file mode 100644
index 0000000..dfe2b09
--- /dev/null
+++ b/src/ui/systems_test.rs
@@ -0,0 +1,57 @@
+use bevy::prelude::*;
+use bevy_ui_widgets::SliderValue;
+use std::time::Duration;
+
+use crate::components::RhythmText;
+use crate::resources::{RhythmState, HighlightTimer, RhythmMode};
+use crate::ui::systems::update_rhythm_from_slider;
+
+#[test]
+fn test_update_rhythm_from_slider() {
+    let mut app = App::new();
+
+    // Set up resources.
+    app.insert_resource(RhythmState {
+        duration: 1.0,
+        mode: RhythmMode::Constant,
+        accelerate_counter: 0,
+    });
+    app.insert_resource(HighlightTimer(Timer::from_seconds(1.0, TimerMode::Repeating)));
+
+    // Spawn an entity with the RhythmText component.
+    let text_entity = app.world_mut().spawn((
+        Text("Rhythm: 1.0s".to_string()),
+        RhythmText,
+    )).id();
+
+    // Spawn an entity with SliderValue and manually trigger the `Changed` state.
+    // The value 1.55 should be rounded to 1.6 by the system.
+    let slider_entity = app.world_mut().spawn(SliderValue(1.55)).id();
+
+    app.add_systems(Update, update_rhythm_from_slider);
+
+    // Run the system once. The initial slider spawn should trigger the `Changed` filter.
+    app.update();
+
+    // Check that RhythmState was updated and rounded correctly.
+    let rhythm_state = app.world().get_resource::<RhythmState>().unwrap();
+    assert_eq!(rhythm_state.duration, 1.6);
+
+    // Check that HighlightTimer was updated.
+    let highlight_timer = app.world().get_resource::<HighlightTimer>().unwrap();
+    assert_eq!(highlight_timer.0.duration(), Duration::from_secs_f32(1.6));
+
+    // Check that the text component was updated.
+    let text_component = app.world().get::<Text>(text_entity).unwrap();
+    assert_eq!(text_component.0, "Rhythm: 1.6s");
+
+    // Test early return for small changes.
+    // Update the slider to a value very close to the current rounded value (1.6).
+    app.world_mut().entity_mut(slider_entity).insert(SliderValue(1.605));
+    app.update();
+
+    // The state should remain unchanged (1.6) because the absolute difference
+    // between 1.6 and (1.605 * 10).round() / 10.0 => 1.6 is 0.0, which is < 0.01.
+    let rhythm_state = app.world().get_resource::<RhythmState>().unwrap();
+    assert_eq!(rhythm_state.duration, 1.6);
+}