# Lesson 21

Zeros in the Standard Algorithm

### Lesson Purpose

The purpose of this lesson is to use the standard algorithm when the minuend has several zeros.

### Lesson Narrative

These problems can be challenging for students because they require special attention to make sense of how the multiple regroupings work and how they are recorded in the standard algorithm.

- Representation

- MLR8

### Learning Goals

Teacher Facing

- Use the standard algorithm to subtract in the ten-thousands when the minuend has several zeros.

### Student Facing

- Let’s subtract from numbers with several zeros.

### Required Materials

Materials to Gather

### Required Preparation

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 20 min |

Activity 2 | 15 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

Which parts of this lesson gave you insight into how students are subtracting across zero? What insights did you gain?