For teachers: introducing Latin and Euler square puzzles
I give each student a baggie with 16 pieces: a square, circle, triangle and rhombus in each colour. Then I ask the students to sort out the pieces, without giving any suggestions about how to do that. If someone seems uncertain what to do in the face of the deliberately vague instructions, I ask them to figure out if any pieces are missing. That seems to provide enough direction to get them going. It’s always interesting to see how many sort by colour, how many by shape, and how many use both at the same time, which is essentially level 1 of the Euler puzzles.
Unlike the way I in which introduce other puzzles to classes, I usually put the rules for these – one level at a time – on the board, as the first students complete each level. That way each student can double-check the rules that s/he is currently using. I think it is useful for students to see the progression in complexity, and for them to realise that the rules are what makes the game. If I don’t put up the next rule quickly enough, students will often suggest it.
Getting the idea across for the lowest level you start at often requires several re-statements, as some people oversimplify and others make it more complicated than necessary. I have discovered that in any age group there are people who can hear a rule and proceed to use it, others who can read it and proceed to use it, others who read a rule and need to re-state it in their own words before using it, and some who need to hear the re-statement from their peers.