Build a countdown timer in Scratch. The project and example diagrams use Japanese labels; the steps below explain the task in English.

Let’s divide seconds, minutes, and hours into units.

Try your hand at “Let’s Make a Digital Clock” and “Let’s Make a Timer 1 (Count Up).”

This time, the “division of units” for hours, minutes, and seconds is already done.

Let’s make a flowchart.

Draw a flowchart for decreasing the remaining time by one second at a time. Decide what should happen when the seconds reach zero, when the minutes reach zero, and when the countdown finishes.

Next, let’s try creating the flow we thought of using a block program.

First, let’s think about a program that changes the “seconds” every second.

How many seconds will it take before the minutes change?

Similarly, how many “minutes” would it take to change the “hour”?

How long can time last?

There is no single algorithm, so it’s interesting to compare your approach (how you calculate the numbers) with your friends!

I think any algorithm that ultimately displays the correct time is “correct”! Please give it a try.

Use the Japanese worksheet below to plan your program and record how it works.

Japanese worksheet →

Open this project on Scratch, select “See inside”, then choose “Remix” while signed in to Scratch. Change the code, pictures or sounds to make your own version. Please credit the original project when you share it.