This afternoon I brought in a recipe to make playdough. Who knew grade 3s would get so excited about playdough?! We read through the recipe and then I showed them the set of measuring cups I had brought from home. I shared a true story with them...that I had been missing my 1-cup measure for quite awhile (I think my sons used it for some sort of experiment in the backyard and it never returned to my kitchen). The students' problem was to figure out how to use the measuring cups we did have (3/4, 1/2, 1/4) to measure out 2 cups of flour.

A few students had an idea right away so I had them share that with the group to get started. They all said they new that a 1/2 and a 1/2 would make 1 cup so then four 1/2 cups would make 2 cups. I asked them to use this same thinking to think about the 1/4 measuring cup. The students were asked to think about as many different ways to use the measuring cups to make some cups. About six children took this challenge on quite seriously and in the time that they had (about 10 minutes) were able to record 5 or 6 ways.

The students used different ways to record the combinations of measuring cups. Some used more visual approaches (pictures of the cups with fractions labeled on them), some used combining and addition notation to show how they combined cups to equal 2 cups and a few students used the multiplication symbol in their recording. Although they were not formally multiplying fractions, they were using their understanding of multiplication and applying it to this context.

This was "big thinking" math for grade 3s but I think because the students could relate to the context and knew we would be using one of the ways to measure 2 cups of flour to actually make the playdough, they were very engaged with this problem.

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