Five pages on adding and subtracting tens, the 1st grade step from facts within 10 to numbers within 100. Page 1 shows ten rods: 3 rods and 4 more rods, or 7 rods with 4 crossed out. Students write the tens (3 tens + 4 tens = 7 tens) and then the number sentence (30 + 40 = 70). Page 2 pairs a fact with its tens fact: 4 + 3 = 7, so 40 + 30 = 70. Then come twelve tens facts up to 100, three with a missing number. Page 3 adds tens to a number that is not a ten, like 34 + 20: students count on by tens in boxes (34, 44, 54) and write the sum. Page 4 hops by tens on an open number line, forward for adding and back for subtracting (78 − 30: 68, 58, 48). Page 5 takes tens away by breaking the first number apart: 86 is 80 and 6, 80 − 30 = 50, and 50 + 6 = 56, with blocks to cross out. Each page starts with a worked example.
Before page 1, hold up 3 ten rods and then 4 more and ask how many tens there are, then how many ones that is. Say it both ways: 7 tens, 70. For page 2, write 5 + 2 = 7 on the board and ask what 50 + 20 must be, and why. On pages 3 and 4, count on by tens out loud from a number like 34, tapping a rod or a hop each time. For page 5, build 86 with blocks, take away 3 rods and ask what happened to the 6 ones (nothing).
Use dimes as tens: 3 dimes and 4 dimes are 7 dimes, or 70 cents. Ask quick questions like "What is 50 + 30?" and "What is 34 + 20?" Count on by tens from any number together: 26, 36, 46, 56. Then count back.
This pack supports the following Common Core State Standards for Mathematics:
© Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
A 5-page 1st grade pack for adding and subtracting tens within 100. Count ten rods to add and subtract tens (3 tens + 4 tens = 7 tens, so 30 + 40 = 70), then use a fact you know: 4 + 3 = 7, so 40 + 30 = 70. Add tens to any number with base-ten blocks, counting on by tens from 34 to 44 to 54, and hop forward and back by tens on an open number line. Last, break a number into tens and ones to take tens away: 86 is 80 and 6, 80 − 30 = 50, and 50 + 6 = 56. Every page comes in color and in black and white. Answer keys included.
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