The students discover that it takes different numbers of rods to measure the height of the picture. They tally the number of each color and then glue the die-cut rods onto the paper. The students made several discoveries. It takes fewer brown rods because the unit is much longer. It takes many more light green rods because the units are much shorter. Because there are ten colors of Cuisenaire rods, all with different lengths, there are multiple opportunities to measure the same object with different units. Students quickly conclude that the smaller the unit, the more it takes to measure the same object. As they measured, they were able to predict how many of each color it would take to measure the picture. Their predictions became more accurate the more colors they experimented with.

This activity lays the groundwork for many later concepts. In later grades, students must find equivalent units (for instance, between inches, feet and yards). In this activity, students were noticing that 2 light green rods equal one dark green rod, and 6 pink rods = 3 brown rods. The activity also relates to finding common multiples (click on the grade 5 link above).

Note to teachers: because the rods are based on centimeters, the picture is 24 centimeters long. That way, all of the rods that correspond to 8, 6, 4, 3, 2 and 1 can be used to measure the picture.