Lesson 12: Sprite Movement
45 minutes
Overview
Question of the Day: How can we control sprite movement in Game Lab?
In this lesson, students learn how to control sprite movement using a construct called the counter pattern, which incrementally changes a sprite's properties. Students first brainstorm different ways that they could animate sprites by controlling their properties, then explore the counter pattern in Code Studio. After examining working code, students try using the counter pattern to create various types of sprite movements.
Purpose
This lesson builds on the draw loop that students learned previously to create programs with purposeful motion. By either incrementing or decrementing sprite properties, such as sprite.x, students can write programs that move sprites in expected patterns, instead of the randomization that they used in the past. The animations that students learn to create in this lesson lay the foundation for all of the animations and games that they will make throughout the rest of the unit.
Assessment Opportunities
-
Use the counter pattern to increment or decrement sprite properties
See Level 8 in Code Studio.
-
Identify which sprite properties need to be changed, and in what way, to achieve a specific movement
See Level 8 in Code Studio.
Standards
AP - Algorithms & Programming
- 2-AP-11 - Create clearly named variables that represent different data types and perform operations on their values.
- 2-AP-12 - Design and iteratively develop programs that combine control structures, including nested loops and compound conditionals.
- 2-AP-13 - Decompose problems and subproblems into parts to facilitate the design, implementation, and review of programs.
- 2-AP-16 - Incorporate existing code, media, and libraries into original programs, and give attribution.
- 2-AP-17 - Systematically test and refine programs using a range of test cases.
- 2-AP-19 - Document programs in order to make them easier to follow, test, and debug.
Agenda
Objectives
Students will be able to:
- Identify which sprite properties need to be changed, and in what way, to achieve a specific movement
- Use the counter pattern to increment or decrement sprite properties
Preparation
- Check the "Teacher's Lounge" forum for verified teachers to find additional strategies or resources shared by fellow teachers
- If you are teaching virtually, consider checking our Virtual Lesson Modifications
Links
Heads Up! Please make a copy of any documents you plan to share with students.
For the teachers
- Sprite Movement - Slides (Download)
- The Counter Pattern - Resource
For the students
- Sprite Movement - Video (Download)
Teaching Guide
Warm Up (5 minutes)
Reviewing Sprite Properties
Review: On a piece of scratch paper, list out all of the sprite properties you can think of and what aspect of a sprite they affect.
Prompt: What kinds of animations could you make if you could control these properties? Consider adding and subtracting from properties, or even updating multiple properties at the same time.
Discuss: Allow students to share their ideas with a partner before sharing with the entire class.
The purpose of this discussion is to start students thinking about how they might use the various sprite properties they've seen so far to make animations with purposeful motion. If students struggle to come up with ideas, you can narrow down the question to specific properties. For example:
Question of the Day: How can we control sprite movement in Game Lab?
Activity (35 minutes)
Transition: Send students to Code Studio.
Guide to Programming Levels: Additional guidance for programming levels is provided in the CSD Guide to Programming Levels. This document includes strategies and best-practices for facilitating programming levels with students.
Questions to Consider with Video:
- What is the counter pattern?
- How does the counter pattern move sprites across the screen?
Goals:
Students may describe the counter pattern in various ways. Make sure that they go beyond just stating the blocks or code that the counter pattern uses. They should understand that the counter pattern allows the programmer to update the value of a variable in a pattern that counts up (or down) on every iteration of the draw loop. This can be used for many different things, such as spinning, growing, shrinking, or timers, but it's most often used to move sprites across the screen.
When a sprite's x or y property is updated in a counter pattern, its position changes in a consistent way over time, causing it to move across the screen. Students should be able to explain that movement in an animation is just a change in position, and that changing a sprite's x position will cause it to move horizontally, and changing a sprite's y position will cause it to move vertically.
Formative Assessment: This level can be used as a formative assessment. A rubric is provided in the level, and written feedback can be given to students. Click here to learn more about giving feedback to students.
Wrap Up (5 minutes)
Journal
Question of the Day: How can we control sprite movement in Game Lab?
Prompt: You've seen two ways to create animations with the draw loop: random numbers and the counter pattern. What is one type of movement that you'd want to use random numbers for? What is one type of movement that you would want to use the counter pattern for? Are there any movements that might combine the counter pattern and random numbers?
Discuss: Allow students to discuss with a partner before sharing with the entire class.
Student answers may vary, but movements such as shaking use random numbers, and movements that are more purposeful use the counter pattern. It's less important that students have a specific answer than that their answers reflect a growing understanding of how the different programming constructs work.
Students may have seen random numbers used on one property (rotation) and the counter pattern used on another (x position) in one of the challenges, but if there is time, encourage them to think about what would happen if you used the counter pattern to add or subtract a random number to a sprite property, or to combine the two constructs in other ways.
This work is available under a Creative Commons License (CC BY-NC-SA 4.0).
If you are interested in licensing Code.org materials for commercial purposes contact us.
