Lesson 3: Building in Scratch
20-30 minutes (can be split into two sessions)
What You Will Learn
In this lesson, you will:
- Set up your Scratch project with the right sprites and backgrounds
- Start connecting code blocks step by step
- Test your project as you build it
- Learn that building takes time and that is perfectly okay
Time to Build!
You have your idea. You have your plan. Now it is time to open Scratch and start building! This is the exciting part -- you get to watch your plan come to life on screen.
Follow these steps in order. Take your time with each one. There is no rush!
Before You Start
Keep your storyboard and planning sheet next to the computer. Look at them often! They are your guide. When you are not sure what to do next, check your plan.
Building Step by Step
Open Scratch and Start a New Project
Go to scratch.mit.edu and click "Create" to start a new project. Give your project a name by clicking on the title at the top. Use the name from your planning sheet!
Set Up Your Background
Look at your storyboard. What does Box 1 (the beginning) look like? Click the background button in the bottom right corner and choose a background that matches your plan. You can pick one from the Scratch library or draw your own.
Scratch Tip
If you need more than one background (for example, a park and then a house), add them all now. You can switch between them later using the "switch backdrop" block.
Add Your Sprites
Look at your planning sheet where you listed the sprites you need. Add each one by clicking the cat button with a plus sign in the bottom right corner. You can:
- Choose a sprite from the Scratch library
- Draw your own sprite
- Upload a picture
If you do not need the default cat sprite, right-click on it and choose "delete."
Build the Beginning First
Look at your step-by-step list from Lesson 2. Start with the very first thing that happens. Click on the sprite that does something first, and start adding code blocks.
Almost every project starts with the "when green flag clicked" block from the Events category. Drag it out and build from there!
Scratch Tip
Build just a few blocks at a time, then click the green flag to test. Does it do what you expected? If yes, keep going! If not, check your blocks and fix any problems.
Add One Part at a Time
Do not try to build the whole project at once. Follow your plan and add one part at a time:
- Get the first scene working.
- Then add the second scene.
- Then add any interactions (clicking, pressing keys).
- Then add sounds or music.
After adding each part, click the green flag and test it. This is called building and testing in small steps. It is how real programmers work!
Connect Your Blocks
As you build, you will use blocks from the categories you learned in earlier modules:
- Events: "when green flag clicked," "when this sprite clicked"
- Looks: "say," "switch costume," "switch backdrop," "show," "hide"
- Motion: "move," "go to," "glide"
- Sound: "play sound," "start sound"
- Control: "wait," "repeat," "if/then"
If you are not sure which block to use, try different ones! Experimenting is part of building.
What If It Does Not Work?
Here is a secret that every programmer knows: things almost never work perfectly the first time. That is completely normal! Remember everything you learned about debugging in Module 6.
It Is Okay If...
- Your sprite moves the wrong way -- just change the numbers!
- Things happen in the wrong order -- rearrange your blocks!
- Something does not look right -- try a different block!
- You change your mind about your plan -- that is creativity!
- You need to take a break and come back later -- building takes time!
Every mistake is a chance to practice your debugging skills. You are not failing -- you are learning!
For Parents: When Your Child Gets Frustrated
Building a project is the most challenging part of this course, and some frustration is natural. Here is how to help:
- Take a break. Walk away for a few minutes and come back with fresh eyes.
- Go smaller. If the project feels too big, help your child simplify it. A finished simple project feels much better than an unfinished complex one.
- Read the blocks out loud. Sometimes saying "when green flag clicked, say hello for 2 seconds, then move 10 steps" helps you hear what is wrong.
- Celebrate what works. Point out everything that IS working, not just what is not.
- Spread it out. There is nothing wrong with building over two or three sessions. Save the project and come back tomorrow!
Saving Your Work
How to Save in Scratch
If you have a Scratch account, your project saves automatically. You can also click File and then "Save now" to save right away.
If you do not have an account, click File and then "Save to your computer" to download your project as a file. You can open it again later with File and then "Load from your computer."
Save often! You do not want to lose your hard work.
Key Takeaways
- Keep your plan next to the computer as you build -- it is your guide
- Set up your background and sprites first, then add code
- Build and test in small steps -- add a few blocks, then click the green flag to test
- Things will not work perfectly the first time, and that is completely normal
- It is okay to build over more than one session -- save your work and come back
- When stuck, try reading your blocks out loud, simplifying, or taking a break
Ready for More?
Next Lesson
In Lesson 4, you will test your project, have someone else try it, and celebrate what you made!
Start Lesson 4Module Progress
You have finished Lesson 3! Your project is taking shape. Wonderful work!
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