Great vocabulary and reasoning task!
What You Need: geoboards and geobands (real or virtual)
How to Play: The leader makes a secret shape on his/her geoboard. Players make shapes then show them to the leader who tells them whether or not they are in the club. Players keep changing the attributes of their shape to try to get in the club.
The club can be simple (a 3-sided figure) or complex (at least 2 90* angles).
This task gives practice with classifying shapes by their attributes, Van Hiele's Stage 2 of geometric development--Informal Deduction.
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