Unit 3, Lesson 10
Subtraction Algorithms (Part 3)
Grade 3
Preparation
Lesson Narrative
In this lesson, students continue to learn how to use algorithms to subtract within 1,000. The new algorithm in this lesson draws attention to how place value can be used to record fewer digits in each place-value position. This condensed notation also changes the steps of the algorithm, because students don't write the numbers in expanded form to start, or add up the partial differences at the end.
- Representation
- MLR8
- Compare and contrast (orally and in writing) subtraction algorithms.
- Explain (orally) how to use an algorithm to subtract.
- Let’s learn another algorithm to subtract.
Required Materials
Warm-up
Required Preparation
None
Teacher Reflection Questions
Who got to do math today in class and how do you know? Identify the norms or routines that allowed these students to engage in mathematics. How can you adjust these norms and routines so all students get to do math going forward?