Regular Polygons with Scratch Teacher ‘cheat sheet’

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This document supports a teacher to scaffold a group of learners to develop their thinking and programming of regular polygons. It is NOT intended as a hand-out for learners. Can you get the cat draw a line?

Encourage learners to experiment with pen blocks and motion blocks . Ask them how they could see the movements of the cat more clearly. Let them experiment with

wait block in the control blocks . Some that are recognising repeating patterns may be ready to try use of the repeat block. How will you start the cat moving? Encourage the learners to try different event blocks . What can you program the cat to draw? Can the Scratch cat write its name? Talk to your friend – how can it draw an S? (You can encourage them to use robot writing which is all in straight lines.) Talking this through will let the children agree on an algorithm. Note: some children will need to be programming at the same time as thinking through the algorithm. It is important to let those children have the concrete movement to let them work through what needs to happen. Some children will be able to talk through the algorithm by drawing it or moving in the shape of an S. One algorithm is suggested here but there are other ways to achieve a square. It can be interesting for children to see different algorithms and to talk through which is the most efficient. Can the cat draw a square? Talk to your friend – what is the algorithm to draw a square? Have a go at programming your square. Wait commands are included here for children to see the cat actually moving rather than the square just suddenly appearing. The wait commands are only needed if this will help learners to understand what is happening. Some learners will use a sequence to draw a square. Look at the sequence, chant the sequence. What is the pattern? Can you use the repeat command?

Can you change your program to draw an equilateral triangle? Can you use your program for a square and program for a triangle to draw a house? Learners using Scratch 2.0 can define a procedure for a square using More

Blocks

Move left Turn 90 left Move down Turn 90 left Move right Turn 90 right Move down Turn 90 right Move left

Regular Polygons with Scratch Teacher ‘cheat sheet’

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Note: It is important that learners have time to try out how they will make the cat move so that the triangle is on top of the square. There are different ways of doing this. They will also need to think through how they make sure the house is the right way up.

How do you make the cat draw a house the right way up each time?

A script is provided here but both the teacher and the learner will gain more from the trial and improvement involved in coming up with your own program. Can you draw a row of houses? What other regular polygons can you draw? Can you draw a circle?

Can you teach the cat to draw any regular polygon? Can you write a program for anyone to be able to draw any regular polygon?

Learners will need to go to the data blocks and use a variable to do this. They will need to identify what is changing each time they draw a different polygon.