This Formative Assessment Unit is intended to assess how well students are able to compose and decompose numbers within twenty. Students should be able to use a range of strategies and be able to explain why these strategies work. Students should be able to think of ten in as many ways as possible. In addition, students should be able to compose and decompose numbers in a variety of ways and to be able to justify their thinking. Students will also be able to develop strategies for determining sums and differences when adding and subtracting. Students should clearly explain their reasoning and justify their thinking.

The unit lesson begins with a pre-assessment, Maria’s Piggy Bank, to determine students’ current level of understandings and misunderstandings. Daily lessons begin with a variety of warm-up activities followed by the main lesson, chosen from the menu activities. The menu activities are designed to be taught as whole group lessons, in small groups, or in partners. The purpose of the menu activities are for students to deepen their conceptual understandings of the activity while teachers have the opportunity to observe and listen to student thinking. The use of sentence frames promotes student structured talk to deepen student’s thinking and mathematical understanding. This is an important time to collect formative assessment information. At the end of the unit, students revisit Maria’s Piggy Bank, which serves as a post-assessment to assess what has been gained from the unit.

Taught by: Liz O'Neill, M.H. Tobias Elementary School, Jefferson Elementary School District, Daly City, California

Mathematical Strands:

- Number & Operations in Base Ten

- Operations & Algebraic Thinking

- Using Base Ten: Base Ten Menu PDF: Lesson plan, student pages, pre- and post-assessments, and supporting instructional materials
- Student Work: How Many Are Hiding PDF: Set 1
- Student Work: How Many Are Hiding PDF: Set 2
- Student Work: How Many More PDF
- Student Work: Maria's Piggy Bank PDF