Lesson: Subtracting by Counting Back: Numbers up to 20 Mathematics • 1st Grade
In this lesson, we will learn how to subtract within 20 by counting back from the starting number.
On this domino, the dots on one side are covered with a sticker, and the total number of dots is written above it.
How many dots are under the sticker on this domino?
Michael holds up 9 fingers and starts counting down as he puts down one finger at a time. He stops when he is holding up 4 fingers.
Decide whether he was adding or subtracting by picking the number sentence that describes what he did.
Emma put her counter on 12 then moved it back 2 spaces.