lesson
One event should not become many points
1 · Learn
If a loop checks a collision repeatedly, a single continuing collision may increase score many times. The program needs a clear rule for when an event counts, such as waiting for separation or marking a target as already collected.
Test the edge case, not only a quick successful run. A score that increases is not necessarily a score that increases correctly.
2 · Worked example
A player touches a coin for several loop cycles. I hide or mark that coin after collection so the same coin cannot award points on every cycle.
3 · Your turn
Why might 'if touching coin, change score by 1' inside a fast loop award too many points?
Check your answer
The condition remains true across repeated checks, so the same contact can trigger repeated increments.
4 · Apply your learning
Create a test where contact lasts several seconds and verify exactly one award per intended collection.
Adult guidance and safety
Use a school-approved offline or supervised tool and fictional data. Keep work private, respect media permissions and check accessibility. Paper traces support understanding but do not replace running, saving and testing a real project. Do not enter passwords, addresses or other personal details into exercises.
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.
Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Practice this lesson
Lesson resources
Browse the available practice activities and worksheets for this lesson.
Your progress