Lesson objective: Students will be able to apply what they know about using place value to add a two-digit number to a multiple of ten.

This lesson provides an opportunity for students to apply their knowledge and understanding of adding a two-digit number to a multiple of ten to a mathematical situation. Students are asked to complete a chart in which various numbers (both total and parts) are missing from a collection of block designs.

Key Concept students will use:

- We can add two-digit numbers by adding tens to tens and ones to ones. (We can add by place.)

Skills students will use:

- Using place value to read, write, and represent numbers (Grade 1, Unit 8)
- Communitive property of addition (Grade 1, Unit 6)

Students engage in Mathematical Practice 5: Using Appropriate Tools to Add as they choose a way to represent the numbers in the chart. Student may use cubes, numbers, or any other tool or strategy they need.

**Key vocabulary: **

- addend
- one
- part
- ten
- whole

**Special materials needed:**