Lesson3

Lesson 3: Interactivity with Events – Make It React!

Theme: “Your program listens and reacts – just like you do!”

Goal

Introduce the concept of events in Scratch using the Conscious Competence model. Students will learn how to make their projects respond to input such as clicks or keys. By the end of the lesson, each student creates a project where a sprite reacts to interaction.

Structure (1.5 hours)

1. Welcome & Recap (10 min)

Teacher Instructions
  • Ask the group: “What did we make with loops last time?”
  • Open Scratch and show a quick demo: when you click a sprite, it changes color or says something.
  • Ask: “How did the sprite know what to do when I clicked?”

Step 1 – Welcome & Recap

2. Guided Build – Click Reaction (15 min)

Teacher Instructions

Guide students step-by-step to build a sprite that reacts when clicked.

Start simple: 1. Create a sprite or use the cat. 2. Add the following blocks to make the sprite talk:

🔧 Code: Sprite Says Something When Clicked

when this sprite clicked
say [Hello!] for 2 seconds
Variation

Let students experiment with visual effects:

when this sprite clicked
change color effect by 25

Encourage creativity: try different looks, sounds, and messages.

Step 2 – Guided Build

3. Break & Reaction Game (10 min)

Teacher Instructions

Use this active break to reinforce the event-driven thinking from coding. The game simulates how a program waits for a specific trigger before acting.

Game: Robot Simon Says

  1. One student volunteers as the Robot Master (or you can be the first one).
  2. They give commands like:
    • “Simon says jump!”
    • “Simon says touch your nose!”
    • “Spin around!”
  3. The rest of the class should only follow commands that begin with “Simon says”.

If someone follows a command without “Simon says,” they sit down or freeze for a turn.

After 2–3 minutes, rotate the Robot Master once or twice.

Link it back to code: - “Your Scratch sprite only moves or reacts when a specific event happens — like being clicked or a key being pressed.” - “Just like you only react when you hear the right command!”

You can even draw the parallel on the board:

when [space key] pressed
say [Jump!]

vs.

(no event → no reaction)

Step 3 – Break Game

4. Mini Challenge (25 min)

Teacher Instructions

Let each student choose one challenge to build on what they learned:

  • A pet that talks when clicked
  • A sprite that changes color or costume when clicked
  • A soundboard that plays different sounds when clicked

Encourage independence, but walk around to assist and challenge students.

🔧 Optional: Add Key Events (For Fast Learners)

when [space] key pressed
say [Jump!] for 1 seconds
when [right arrow] key pressed
change x by 10

Step 4 – Mini Challenge

6. Closing & Next Step (10 min)

Teacher Instructions

Wrap up the session:

  • Ask: “What kind of things can events do?”
  • Ask: “What would you like your sprite to react to next time?”
  • Tease next lesson: “We’ll make a sound machine or mini-music game!”

✏️ Optional Homework

  • Have students draw or describe a sprite that reacts to:
    • Touch
    • Sound
    • Key presses