Lesson 15

The purpose of this lesson is for students to write and solve their own Put Together/Take Apart, Both Addends Unknown story problems.

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. In previous lessons, students represented and solved Put Together/Take Apart, Both Addends Unknown story problems. This lesson builds on students’ experience in the Math Stories center.

In this lesson, students use familiar contexts to generate and solve Put Together/Take Apart, Both Addends Unknown story problems. In the second activity, students are encouraged to find all possible solutions and use reasoning based on patterns explored in previous lessons (MP8).

When students attend to the mathematical features of a situation, adhere to mathematical constraints, make choices, and translate a mathematical answer back into the context they model with mathematics (MP4).

• Each group of 2 needs 1 connecting cube.

• Each group of 2 needs at least 10 two-color counters.

What language did students use as they made up their problems? How has the language that students use progressed throughout the unit?