' Dr Ell's Math Blog: What Fits?

Wednesday, December 2, 2009

What Fits?

     This is a Cuisenaire Rods game that lets your child begin to 'see' or 'feel' or 'sense' math relationships. The object is to start with a given rod, say the orange one, and 'fit' other rods to it.  Two yellows fit. A dark green and a purple fit, too. Ten white rods fit. And so on.

     No numbers need to be assigned, but they will come eventually. An orange rod is ten units long and the rods that 'fit' are the numbers that add up to ten. I think it's important to just go with colors and size and feel for quite a long time and let the game be open-ended. When arithmetic finally does come up it will seem perfectly reasonable that 5 + 5 = 10 because "of course" yellow and yellow fit orange. I find it helps some children to verbalize the relationships just that way: "Look, Mom-- brown and red make orange"  or "Green and red fit yellow."
     Cuisenaire sells a little frame with their basic sets that make 'fitting' the rods easier for little people. This frame is especially useful if the game is amplified to include more than two pieces in a 'fit' and if the 'fits' are stacked up into a pattern or design. These 'rugs' are a lot of fun to create. Some pictures of individual fits as well as rugs follow.

     As children get older and more experienced, the game can be amplified to include 'fits' to double length rods. For instance, the question could be asked, 'What fits two brown rods?' Fits can also be more challenging if the player is limited to a single color answer. For orange this would require two yellow rods or five red rods. For 'odd' size rods, like yellow, there is no single color answer. That problem is solved if a single white rod is permitted when needed. In that case, yellow could be fitted with two red rods and a white.


  1. I had forgotten about that nifty frame board thing, what is it called? I would like to look for something like that for S to line blocks up more easily...

  2. Wow-- good question. I got my frames years ago and have taken them for granted. I went looking for them in order to respond here and have found none. It may be that they don't make them anymore, which would be too bad. I did find a reasonable substitute, though. Education Resources sells a set of ten trays by Numicon that are sized for Cuisenaires. The orange tray will hold rods up to orange size. Unfortunately, all the trays have four sides which will limit the length of the rugs to be produced.