Cut four triangles from a square as shown in the picture. How many
different shapes can you make by fitting the four triangles back
What is the greatest number of squares you can make by overlapping
In this town, houses are built with one room for each person. There
are some families of seven people living in the town. In how many
different ways can they build their houses?
"This was fun," we heard from many people who moved the circles
around as they tried to find out how to rebuild the triangle so it
faced in the opposite direction. Gerrit did very well to put into
words what you needed to do:
"To change the triangle's direction with only three moves, move
the outside bottom row balls to the second row from the top, and
move the top ball to the bottom."
Easy when you know how!