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For this task, you'll need some blocks of different shapes and colours, or you could print off and cut out the shapes on this sheet.
Choose a rule, like 'only have four-sided shapes' or 'only have large shapes'.
Challenge someone else to work out your rule.
They can do this by choosing a shape for you to say either "Yes, that obeys my rule and is in my set" (you then put it over on the left) or "No, this does not obey my rule and so is not in my set" (you then put it over on the right).
How did they decide which shapes to choose?
Did they get quicker at finding out the rule?
What was the smallest number of shapes they needed to try?
Could you make some more shapes to add to the set? What would you make and why?
Tell us about some of the rules you chose and how you decided which shapes to try.
Why do this activity?
This activity can be used to build up children's confidence with the language associated with 2D shape.
You can do this activity as a whole class, teacher-led activity, by creating shapes on the interactive whiteboard. Choose a particular property and drag a shape which meets that criteria to the left of the screen underneath a title of something like 'These shapes are in my set', or simply 'Yes'. (Alternatively, you could print off, laminate and cut out shapes from this sheet and stick them to the board.)
The first time you do this it's a good idea to conduct it in silence. Children take turns to come to the front and select a shape. Without saying anything, you drag it to the appropriate side of the screen. When they think they know your rule they could write it down on their whiteboards.
Once they become familiar with the game, you can interrogate them about their choices. 'Why did you choose that one?'; 'I'll put that one here - what does that tell you?'.
You could then give out sets of the shapes to pairs of children for them to try themselves (if you have 'logiblocks' these are ideal, otherwise print off shapes from the sheet). In this way, you can use the same activity to highlight different properties of shapes so it can be returned to many times over the course of an academic year.
Why did you choose that one?
I'll put that one here - what does that tell you?
Which would be a good one to choose now? Why?
For a class that is less confident, you could scaffold their learning by writing several different rules on the board. They then know that your rule is one of those and can choose accordingly. Children could make up their own rule for you to write.
Challenge children to use as few shapes as possible to test their ideas.
Can you make five differently sized squares from the interactive tangram pieces?
This practical challenge invites you to investigate the different squares you can make on a square geoboard or pegboard.
This activity investigates how you might make squares and pentominoes from Polydron.