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 found the value of sums within 100 using methods based on place value and the properties of operations, including adding tens and tens and ones and ones, and adding on by place. In this lesson, students apply these methods to make sense of and solve real-world problems within 100. Students may use base-ten representations or equations to represent their thinking.

In the Warm-up, they are introduced to a food drive context which will be used throughout the lesson as students use data about the number of cans collected by each grade to determine how the cans should be packed in boxes. Students combine quantities of cans in different ways. Students make choices about which numbers to combine based on their values and the constraints of the problem. Then students are asked to think about the different ways the cans can be packed and choose a way they think makes the most sense.

Reflect on a time your thinking changed about something in class recently. How will you alter your teaching practice to incorporate your new understanding?