Lesson objective: Apply the compensation method to decimal number multiplication.

This lesson provides an opportunity for students to apply their knowledge and understanding of using the compensation method to multiply decimals to a real-life situation. Students are asked to calculate the weight of characters on other planets based on the formula mass x gravity = weight.

Key Concept students will use:

- The meaning of multiplication is the same whether you are working with decimals or whole numbers.

Skills students will use:

- rounding decimal numbers (Grade 5, Unit 6)
- multiplying and dividing by factors of 10 (Grade 5, Unit 4)
- multiplying multi-digit whole numbers (Grade 4, Unit 14)

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they consider what the most efficient strategy is to solve the problem. They use their knowledge of place value and estimation to check if their answers are reasonable.

**Key vocabulary: **

- compensation strategy
- efficient
- gravity
- mass
- weight