diff --git a/content/2-templating/6-conditional/marko/TrafficLight.marko b/content/2-templating/6-conditional/marko/TrafficLight.marko
index 570ae11b..0a1c3c4e 100644
--- a/content/2-templating/6-conditional/marko/TrafficLight.marko
+++ b/content/2-templating/6-conditional/marko/TrafficLight.marko
@@ -1,12 +1,9 @@
 static const TRAFFIC_LIGHTS = ["red", "orange", "green"];
 <let/lightIndex = 0/>
-<let/light = TRAFFIC_LIGHTS[lightIndex]/>
+<const/light = TRAFFIC_LIGHTS[lightIndex]/>
 
 <button onClick () {
-    lightIndex++;
-    if (lightIndex >= TRAFFIC_LIGHTS.length) {
-      lightIndex = 0;
-    }
+    lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length;
   }>Next light</button>
 <p>Light is: ${light}</p>
 <p>
diff --git a/content/3-lifecycle/2-on-unmount/marko/Time.marko b/content/3-lifecycle/2-on-unmount/marko/Time.marko
index c8471dea..a17f1d23 100644
--- a/content/3-lifecycle/2-on-unmount/marko/Time.marko
+++ b/content/3-lifecycle/2-on-unmount/marko/Time.marko
@@ -1,6 +1,6 @@
 <let/time = new Date()/>
-<lifecycle() {
-  onMount () { this.timer = setInterval(_ => time = new Date()), 1000) }
+<lifecycle
+  onMount () { this.timer = setInterval(_ => time = new Date(), 1000) }
   onDestroy () { clearInterval(this.timer) }
-}/>
+/>
 <p>Current time: ${time.toLocaleTimeString()}</p>
diff --git a/content/6-form-input/2-checkbox/marko/IsAvailable.marko b/content/6-form-input/2-checkbox/marko/IsAvailable.marko
index 5257ec92..8d2d272c 100644
--- a/content/6-form-input/2-checkbox/marko/IsAvailable.marko
+++ b/content/6-form-input/2-checkbox/marko/IsAvailable.marko
@@ -1,5 +1,5 @@
 <input#is-available
   type="checkbox"
-  checked:=isAvailable
+  checked:=input.isAvailable
 />
 <label for="is-available">Is available</label>
diff --git a/content/6-form-input/3-radio/marko/PickPill.marko b/content/6-form-input/3-radio/marko/PickPill.marko
index b9e66f47..bebf8b88 100644
--- a/content/6-form-input/3-radio/marko/PickPill.marko
+++ b/content/6-form-input/3-radio/marko/PickPill.marko
@@ -1,8 +1,7 @@
-function handleChange (event) {
-  picked = event.target.value;
-}
-
 <let/picked = "red"/>
+<const/handleChange(event) {
+  picked = event.target.value;
+}/>
 
 <div>Picked: ${picked}</div>
 <input#blue-pill