Traffic light sequence with messages

This time we’ll use ScratchJr to recreate a real life “animation” – a traffic light sequence.
This exercise not only teaches how to implement messages in ScratchJr, but can also serve as an excellent supplement to any road safety lesson or talk.

First, talk to your students about traffic lights. Find out if they know how such lights work, what colors the lights are and what each of the colors means. Make sure they know what order the lights turn on and off in – it’s a sequencing exercise, after all.

In the downloads section below the post, you’ll images for the particular color phases of the signalling device. Print those out and start working with your pupils by putting the lights in the correct order. Those print-outs, left somewhere handy and where everybody can see them, may serve as a crib sheet of sorts when the kids are preparing their own animations.

Traffic lights images – you can get them in the downloads section below this post .

Be careful, though, as different countries may use some slightly varying versions of the signalling device. This post contains solutions for two popular versions of the light sequence:

Source: Wikimedia Commons

Standard sequence in the United States: green – yellow – red – then green and the cycle repeats.

Source: Wikimedia Commons

In the UK and most of the European countries, the sequence goes: green – yellow – red – then red and yellow.

Next, you can play for your students the animation you prepared beforehand. Decide together what sort of background the animation should play out against, what characters to put where, and then, which scripts to use and how to employ the message blocks in order to recreate the effects of your sample project.

Standard US sequence

Individual lights turn on upon receiving a message in the relevant color. The green lamp character waits for the green message. When it receives one, it lights up for a moment, turns off… and sends out a yellow message in order to let the yellow lamp know it’s its turn.

See the solution below:

UK sequence

The UK sequence is more complicated and the task gets more challenging, as you’ll need a fourth message color to create this animation. This time, the red lamp and the yellow lamp characters must act differently in two different situations.

See the solution below:

I assume that all three lamps are initially hidden.

If you’d like the signalling devices to turn on and off in a more dynamic fashion, add a “quick” speed change block at the beginning of each character’s script. This way the characters will disappear instantly instead of fading out.

How do you like this idea? Let me know in the comments!

4 comments

  1. This is an excellent project Weronika. I’m still learning how to use ScratchJR. Hope to find out how to draw perfect circles like you!

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