Read with an adult. Take your time. You can say, point, draw or write your answer.
1 Let's look together
Sometimes a program does not do what we wanted. A bug is a mistake in the instructions. Debugging means finding and fixing it.
Check one step at a time. Change the step that causes the problem, then test from the same starting place again.
Wanted: 2 steps forwardProgram: forward, forward, forwardFix: remove the last forward
Look, point and talk with your adult.
2 Watch how I do it
My robot goes one square too far. I trace three forward commands. I remove the last one and test again from the start.
3 Your turn
You want one step, but your program says forward, forward. What can you change?
Have a go before opening the answer.
Let's check together
Remove one forward command, then test again from the same start.
4 Try it away from the page
An adult makes a short program with one mistake. Find it by tracing. Explain what you changed and why.
Try a real program
Help the robot reach the flag
Start at the top-left, facing right. The flag is at the bottom-right. Say where you think your robot will finish before you run it.
Forward moves one square the way the robot faces. Turn left and Turn right turn on the spot. They do not move into another square.
What happened? · command trace
Find and fix: try Forward, Forward, Forward. Which command hits the edge? Remove it. Add Turn right, Forward, Forward. Reset and test your new program.
Practice only. Your program and trace stay on this page and disappear when you reload or leave. This tool sends nothing, saves no score and does not mark a lesson complete.
Open your writing and drawing pad
Write, draw or show your working. Use a mouse, pen or finger. This pad is not a submitted answer.
Not saved to your account. Download your drawing as PNG and your typed notes as TXT before leaving or refreshing. They are separate files. Do not enter private information.
Open a picture saved on this device to draw on it again. Opening replaces the drawing, but Undo can restore it. PNG only, up to 4 MB and 4096 × 4096 pixels. The picture stays in this browser; it is not uploaded. Paper lines in a saved picture become part of that picture.
Clear the drawing? Your typed notes will stay. You can undo this action.
Your pad is empty.
Open a UTF-8 TXT file from this device, up to 40 KB and 10,000 characters. It stays in this browser. Opening can be undone until you type again. Downloads keep a new copy; they do not change the file you opened.
Replace the notes on this page with the opened file? Download the current notes first if you want to keep them.
Typed notes are not submitted answers.
Explore and practise freely. Opening this lesson or using the writing pad does not save completion or a score.
Adult notes · prerequisites, safety and coverage
Treat mistakes as information, not failure. Keep a record of intended outcome, original steps and revised steps. No claim that watching a diagram equals programming practice.
Computing is the curriculum subject name. KS1 expectations span Years 1 and 2; this is our Year 1 introduction. Stay with the child, use school-approved tools, and practise on a device as well as on paper. Never enter real passwords or personal information in exercises.
Create and debug simple programs (KS1 introduction).
Predict a simple program's behaviour (KS1 introduction).