This lesson is optional because it does not address any new mathematical content standards. This lesson does provide students with an opportunity to apply precursor skills of mathematical modeling (MP4). In previous lessons, students made estimates about the volume of recyclable garbage produced at their school. In this lesson, students make similar estimates and calculations, but now they estimate the weight of food waste produced. In the first activity, students estimate the amount of food waste produced by a single person and by different groups of people during different intervals of time. In the second activity, students are introduced to a food-waste journal and make some initial calculations about their own food waste.

The last activity is optional and can be used after students use the journal to record their food waste for a week. Students share what they notice and compare the amount of food waste they produce to the national average. Students use this sample data to further refine their estimate of how much food waste they produce both monthly and annually.