Page 52 - TG_G1_CH6_CHRIS

Subtract Tens

Write the missing number. Have children look at the picture. Ask:
• Ashley’s apple tree has 30 apples. She picked 10 apples to make an How many apples are on the tree? 30
apple pie.
• Cross out the apples Ashley picked. How many apples does Ashley pick? 10
• Write how many apples are left on the tree. How many apples are left? 20
Can you write the subtraction sentence? 30 –10 = 20

ANCHOR ACTIVITY

Use the Anchor Activity for this lesson as a warm-up to gauge
children’s prior knowledge and help them engage at the
30 − 10 = 20 beginning of class.

1.NBT.6 Subtract multiples of 10 in the range 10–90 from multiples of 10 in the range 10–90 (positive or zero differences). Using concrete
models or drawings and strategies based on place value, properties of operations and/or the relationship between addition and
subtraction, relate the strategy to a written method and explain the reasoning used.
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TIME TO LEARN
TIME TO LEARN

Tens Ones
5 0 You already Ensure that children know that 1 ten is the same as 10, 2 tens is the same as 20,
− 2 0 know 5 – 2 = 3. 3 tens is the same as 30, and so on.
3 0 Review the concept of counting back tens, and check that children
50 − 20 = 30
can count in 10s to 120. Remind children that there is a relationship between
counting back and subtraction. Also, they can use the basic facts of
subtract
STEP tens subtraction to make subtracting tens easier. Write 50 – 30 on the board. Guide
BY Subtract.
STEP children to model the first number using base-ten blocks.
1 70 − 10 = 60 3 30 − 30 = 0 Take away the second number in order to find the difference.
Ask: How many base-ten rod do you have? 5
Say, If you take away 2 base-ten rods, how many base- ten rods do you have
2 90 − 50 = 40 4 4 tens − 2 tens = 20 now? 3
What is the difference between 5 tens and 2 tens? 3 tens
What is 3 tens equal to? 30
5 Tens Ones 6 Tens Ones 7 Tens Ones
4 0 9 0 7 0
− 1 0 − 4 0 − 6 0
3 0 5 0 1 0

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