Page 57 - TG_G1_CH6_CHRIS

6 - 9 Think Addition to Subtract Tens
WARM-UP

On Level

Standard
1.NBT.C.6. Subtract multiples of 10 in Time: 10 minutes
the range 10-90 from multiples of 10
in the range 10-90 (positive or zero Material: 2 empty boxes, 50 counters WHOLE CLASS
differences), Using concrete Instruction: Show children 2 boxes. One box contains 20 counters and the other is
models or drawings and strategies empty. Hand out 30 counters. Say: Put these counters in the second box. Ask: How
based on place value, properties of many counters are there in two boxes together? Empty the first box. Ask: How many
operations and / or the relationship counters now are the second box?
50 – 20 = 30
20 + 30 = 50
between addition and subtraction;
relate the strategy to a written
method and explain the reasoning
used. Reteach
Objective

Subtract tens using the relationship Time: 10 minutes
between addition and subtraction. WHOLE CLASS
Essential Question Material: Cubes
Instruction: place children in small groups. Give each group 30 cubes. Say: Take 20
Can we write the addition sentence cubes away. Ask: How many cubes are left? Write the subtraction sentence.
as a subtraction sentence? 30 – 20 = 10 cubes
Ex. : 40 + 10 = 50
We can write it as
50 – 10 = 40
50 – 40 = 10 Enrich

Ready to Go

Say: During the last lesson you studied Time: 10 minutes
subtracting tens. Today you will study PAIRS WORK
thinking addition to subtract.
Instruction: copy this diagram on the board. Say: This table is an addition table. You
see from this table that 6 + 4 = 10. Ask: Can you complete the table?
Note: Guide children to complete the table. Ask: What is 3 + 5? What do you get if
you add 3? What is 4 + 3? What number do you add to 5 so that the sum is 9? What
is 4 + 4? 1 + 6? 5 + 6?

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