Lesson 5.2: Cloning Sprites

Learning Objectives

Students will be able to…

• Demonstrate the difference between sprite and global variables.

• Explain how cloning and prototyping simplify similar sprites in the same program.

• Create prototype sprites and clones of the prototype sprite

• Explain the difference between a “master” sprite and a “clone” sprite.

Materials/Preparation

• Do Now 5.2: Star Wars Troopers

• 5.2 Slide Deck

• Lab 5.2 handout Lots of Balls(docx) (pdf)

• Test out the lab on student machines before class (cloning in Snap! can bring the web browser to a crawl on some machines).

• Unit 5 Tips

• Video Resource: https://youtu.be/KTemYEzAQZQ

Pacing Guide

Duration	Description
5 minutes	Welcome, attendance, bell work, announcements
15 minutes	Introductory discussion
30 minutes	Lots of Balls lab
15 minutes	Debrief and wrap-up

Instructor’s Notes

Introductory discussion

Example Game

Show students a brief video demonstrating space invaders.

Discussion

• Ask students to think about how we create all the “invaders”?

  • Answer with current knowledge: make one invader sprite, and copy it many times while adjusting the copies as necessary.

• Ask what might go wrong or be bad about this approach.

  • If anything in an invader changes, it will need to be changed many times.

  • Lots of sprites clogging up the program that are all basically doing the same thing.

Demonstration

• Introduce cloning as the automated way of doing the manual copying

• Demonstrate how to create a clone using:

  

• Point out that clones inherit all aspects of the “master” or “prototype” sprite, including scripts.

• Emphasize the importance of using When I start as a clone block to ensure clones don’t duplicate out of control.

  

Activity

• Students should complete the Lots of Balls lab.

• This lab will be repeating much of what was in the lesson. This is intentional.

• Students should focus on ensuring they are differentiating between “master” sprites and “clone” sprites, and that the stage is serving as the main “driver” for the program.

Accommodations/Differentiation

• Advanced students can attempt to assign properties to clones (color, size, etc.) so that not all clones look alike. To do this, they will need to use a global variable to temporary hold the value that can be “claimed” by the clone.

• Struggling students should focus on just creating a single clone from the prototype and not worry about creating multiple clones.

Forum discussion

Lesson 5.2: Cloning Sprites (TEALS Discourse account required).