The activity on this day: Making balance scales (Family Math, p. 98). Pictured above, our most successful balance scale, made with an egg carton, a wire coat hanger and string. Below, a simple balance scale made with a ruler, paper clips and cupcake papers. I'd recommend those tiny paper cups instead of cupcake papers. The cupcake papers were a little too flimsy, though they had the distinct advantage of already being in the cupboard.
A balance scale makes so much more sense after you've built one. It gave my fine young first-grader a chance to experiment. How do you make a scale that balances? Where does the fulcrum go? Why? We spent a good 45 minutes or more on this activity until one of us got distracted by the shiny buttons.
You can see the younger gents entertaining themselves in the background with our real balance scale and the counting bears. First grade gent started his pencil and paper math. He was a little stumped by problems like 5 + __ +2 = 12. We talk regularly about solving strategies, mostly when first grade gent asks me, "Mom, what's 12+7?" ("What is 12+7, my dear?" I ask. "What strategy can you use to find the answer?" When he gets frustrated I tell him to blame Grandma Karen, who always said things like, "Look it up, dear," even though we both knew that she knew the answer already. Moms.) Knowing how to choose a strategy to solve a problem is a crucial math skill. When we're adding, we can memorize addition facts, count on our fingers, draw number lines, use the cuisenaire rods. Today the balance scale was serendipitously right there. So we made it into an addition balance scale. The problem must balance to make the equal sign true. How many must we add to make the sides even?
Speaking of serendipity and the balance scale, the next day my fine young gents paper-and-pencil math book started a new unit on balance, weights and using a scale.