Introduction to the Catch Game

In this lesson, we will create a fun catch game using Scratch.

• One sprite will act as the player and catch other sprites.
• The player sprite will be controlled using the mouse pointer.
• This lesson helps students understand movement, sensing, and conditions in Scratch.

What Students Will Learn

• Control a sprite using the mouse pointer
• Move sprites using motion blocks
• Repeat actions using forever loops
• Detect touch between sprites
• Use if-then conditions
• Hide and show sprites
• Add sound effects
• Duplicate sprites

Adding Sprites

In this project, we will use two main sprites:

• Shark sprite – the player
• Small fish sprite – the object to be caught

How to add sprites:

1. Click on the Choose a Sprite icon at the bottom right corner
2. Select a shark sprite from the library
3. Click again on Choose a Sprite and select a small fish sprite

Changing the Background

1. Click on the Choose a Backdrop icon
2. Select an underwater background
3. This background matches the theme of the shark and fish game

Coding the Shark Sprite (Player)

Starting the Code

• Select the shark sprite
• Go to the Events category
• Drag the when green flag clicked block

Explanation: This block tells Scratch to start the game when the green flag is clicked.

Making the Shark Follow the Mouse Pointer

• Go to the Motion category
• Drag the point towards mouse pointer block

Explanation:

• The mouse pointer is the arrow that moves on the screen
• This block makes the shark face the mouse pointer

Repeating the Action

• Go to the Control category
• Add a forever block
• Place the point towards mouse pointer block inside it

Explanation: The forever block repeats the code continuously.

Moving the Shark

• Go to Motion
• Add the move steps block inside the forever loop
• Change the value to 3 or 4 for smoother movement

Coding the Small Fish Movement

Starting the Fish Code

• Select the small fish sprite
• Go to Events and add when green flag clicked

Making the Fish Move Randomly

• Go to Motion
• Add glide 1 second to random position

Explanation: This block makes the fish glide smoothly to random places on the stage.

Repeating the Movement

• Go to Control
• Add a forever block
• Place the glide block inside it

Using Touch Detection

Understanding Touching

• Sprites can sense when they touch another sprite
• Touching is handled using sensing blocks

Creating the Touch Code

• On the fish sprite, add another when green flag clicked block
• Go to Control and add an if then block

Explanation:

• If-then checks a condition
• If the condition is true, the code inside runs

Detecting Touch

• Go to the Sensing category
• Pick touching and change it to touching shark

Hiding the Fish

• Go to Looks
• Add the hide block inside the if-then block

Repeating the Check

• Add a forever block around the if-then block
• This allows Scratch to check the touch condition continuously

Showing the Fish When the Game Starts

• When the fish hides, it should appear again when the game restarts
• Go to Looks
• Add the show block with when green flag clicked

Adding Sound Effects

• Go to the Sounds tab of the fish sprite
• Click Choose a Sound
• Search for a bite sound and add it

Adding the Sound to Code:

• Go to the Sound category
• Add play sound until done
• Place it near the hide block

Duplicating Fish Sprites

• Right-click on the fish sprite
• Click Duplicate

Explanation:

• Duplicating a sprite copies all the same code
• You can change the costume of each fish to make them look different

Summary of What Students Learned

• Control a sprite using the mouse
• Move sprites smoothly
• Use forever loops
• Detect touching
• Hide and show sprites
• Add sounds
• Duplicate sprites

Task for Students

Create your own catch game:

• Choose any sprite as your player
• Add at least two sprites to catch
• Try changing speed, background, or sounds