Beta. This is a preview. It is the one task we have put into English so far; everything else exists in German only. It is not finished either: it is still being trialled in classrooms, and it still has rough edges.
Similarity classes
Sort the cards so that each group holds similar figures. Above each group, write down what you sorted them by. If you need more groups, add one with the plus — and a figure on its own is a group too.
