Learning how to subtract multiples of 10 from other multiples of 10 is a first grade Common Core math skill: 1.NBT.6. Below we show two videos that demonstrate this standard. Then, we provide a breakdown of the specific steps in the videos to help you teach your class.
Your students should be familiar with counting from 1 to 100 using 1’s and 10’s, starting from any number. They should also be able to read, write, and represent objects using numbers between 0 and 20 (K.CC.1-3).
Later on, understanding place values will enable your students to skip-count within 1000 (counting by 5’s, 10’s, and 100’s). They will also be able to read and write numbers by using “base ten numerals, number names, and expanded form” (2.NBT.1-3).
Common Core Standard: 1.NBT.6 - Subtract multiples of 10 by other multiples of 10, within the range 10-90
Students who understand this principle can:
2 Videos to Help You Teach Common Core Standard: 1.NBT.6
Below we provide and breakdown two videos to help you teach your students this standard.
Video 1: Subtract Multiples of 10 with Base-Ten Blocks
The video starts by introducing the lesson, explaining the students can write the problem down and/or use base-ten blocks to help them solve the problems. Then the video reminds students of two things:
Then the video goes into how to subtract multiples of 10. The first problem is 50 - 20 = ?
Then the video tries another subtraction problem, this time counting backwards.
The video ends by reminding students that when subtracting multiples of ten, they can count back by 10 to solve the problem.
Video 2: Word Problem Practice
This short video walks through a simple word problem, demonstrating how to subtract a multiple of 10 by another multiple of 10. Below is the word problem.
“Carl had a bag of 70 marbles, but he tripped on the sidewalk and 40 rolled down a storm drain. How many marbles does Carl have left?”
The video then summarizes what happened by saying that we started with 70 marbles, subtracted 40, and ended up with 30 for the correct answer.
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