 # Subtraction + Regrouping

8-10 yrs old

Math & Economics

Students will view and build math models of base 10 subtraction problems. Submitted By: Minecraft Education

May 15, 2020

#### Skills

• Creativity
• Critical Thinking

### External References

Associated Engage NY module and lesson.

### Learning Objectives

• CCSS.MATH.CONTENT 4.NBT.B.4 Fluently add and subtract multi-digit whole numbers using the standard algorithm.

### Guiding Ideas

Materials:

Headphones with mics, Math notebooks and pencils (colored pencils and graph paper are good for this too)

Whiteboard and markers

Begin the class with a discussion leading around these questions:

1) What is regrouping?

2) How does regrouping work with addition?

a) Do an addition problem or two with them using the standard algorithm

3) In addition we regroup forward, is it possible to regroup backwards?

4) Can I trade one \$10 bill in for ten \$1 bills?

Next Unveil the big idea:

Regrouping can go backwards in subtraction

### Student Activities

To begin, show and explain a 3 digit subtraction problem that uses the standard regrouping algorithm then have students load the attached single player Minecraft world focused around Subtraction.

Students will load the attached Subtraction world, watch instructional videos and build three subtraction problems in Minecraft. Students are encouraged to co-teach and share their knowledge with one another. Students will document their work in portfolios.

Problem 1: Subtraction Regrouping not needed

Problem 2: Subtraction with Regrouping

Problem 3 Subtraction Regrouping Across Zero

Bonus: Make a Video

When a student finishes all three problems they will work together on the 4th problem. Their goal will be making a “how to” video of them explaining how they solved the problem. If a student finishes a video they should help a teammate make one.

Debrief Questions

1) How is regrouping the same and different between addition and subtraction?

2) Can I trade in one \$10 bills for ten \$1 bill?

### Performance Expectations

The student did all of the following:

1) The student was able to build,regroup, and solve three base 10 subtraction math model.

2) The student was able to make a video of themselves solving and subtraction problem with regrouping.

3) The student was able to write the standard algorithm for subtraction along with their models.

#### Skills

• Creativity
• Critical Thinking