Students in K-3rd grade typically don't know how to multiply and divide, and they don't know fractions, decimals, and percentages. They aren't proficient in adding or subtracting. However, these children are still able to do a lot of mathematical activities that involve spatial reasoning and logic. They are clever and they enjoy puzzles.
In February, I devoted a 45 minute K-3rd grad Math Circle session to matchstick puzzles: Given pictures of arrangements of matchsticks (toothpicks work quite well), rearrange them into different pictures in a specified number of moves.
The puzzles I gave out were puzzles I found on the internet and downloaded. There are lots of options for these types of puzzles if you search for "matchstick puzzles." For example, I found a nice collection of puzzles here:
http://www.learning-tree.org.uk/stickpuzzles/stick_puzzles.htm
I brought a large box of toothpicks, and distributed toothpicks to each table. I also gave a sheet of puzzles to each child to work through. We started by talking about one or two puzzles as a class, then I let students work through others on their own, in whatever order they preferred.
Some things to think about if you try this with your group:
First, a lot of the puzzles I gave out were extra challenging, although not all were. If I were to do this activity again, I would number the puzzles according to difficulty level, so it would be very clear which puzzles were extra hard. A couple of the children found their puzzle to be too hard and gave up. They needed more easy puzzles to try at the beginning to help them warm up to the hard ones.
Second, I would spend more time doing group puzzles. After letting the children work for a while on just two or three puzzles, I should have called them back together to talk about solutions, to let them experience the fun of showing others in the group how to solve it, to give them all the feeling of accomplishment. Instead, with everyone working individually, many of the children wanted to show me their solutions to separate puzzles at the same time. There were too many puzzles and not enough of me! If I had arranged things better, the students would have been showing puzzles to each other, not just me!
Third, probably related to the other two items above, this activity seemed to require more parental assistance than others I've done. Adults could help the children set up the puzzles, talk about which moves were legal, give encouragement, and help the children move to new puzzles when they got stuck. One on one attention seemed important. If you are trying this in a large group of young children, I strongly encourage you to bring along a parent or other adult for each child (or maybe every two children) to help out.
In any case, although my implementation of this activity was rough, I still think matchstick puzzles can be a great activity for children this age. Let me know in the comments if you have ideas that seemed to work well for you.
