Addition Strategies: Models & Number Lines
Introduction:
- In this session, you will learn to solve addition problems using different addition strategies.
- In the previous session, we learned about addition using place value.
ADD 45 + 27
Add ones first.
5 ones + 7 ones= 12
12 has 1ten 2ones.
Now add tens.
4tens + 2tens+ 1ten= 7 tens.
Then add 7tens+ 2ones= 72.
Q1. Add 18 + 29, draw blocks or open number line to help.
8 + 9 = _____
10 + 30 = _____
18 + 29 = _____
18 + 29 = ?
8 + 9 = 17
10 + 30 = 40
18 + 29 = 47
Q2. Shan painted 57 wall paintings. Then he painted 19 modern arts. How many
paintings did he paint? Write an addition equation to show the problem.
57 + 19 = ____
7 + 9 = ___
50 + 10 + ___ = ____
___ + ____ = ____
Answer:
57 + 19 = ?
Add ones
7 + 9 = 16
Then add tens.
50 + 10 + 10 = 70
70 + 6 = 76
57 + 19 = 76
Q3. A chessboard has 32 black squares and 32 white squares.
How many squares do they have in all? Use any of the strategies
You have used?
Number of black squares = 32
Number of white squares= 32
Total squares. = 32 + 32
Use models and add.
Add tens.
3tens + 3tens= 6tens
Then add-ones
2ones + 2ones= 4ones
6tens + 4ones= 64
Q4. Find 25 + 19 in different ways.
25 + 19 = ?
Add ones.
5 ones + 9 ones = 14
14 has 1 ten + 4 ones
Add tens
2 tens + 1 ten + 1 ten = 4 tens
4 tens + 4 ones = 44
So, 25 + 19 = 44
Draw tens and ones and find the answer.
25 + 19 = ?
Add ones.
5 ones + 9 ones = 14
14 has 1 ten and 4 ones
Add tens
2 tens + 1 ten + 1 ten = 4 tens
4 tens + 4 ones = 44
25 + 19 = 44
Q5. Add 35 + 16 on an open number line.
16 has 1ten + 6 ones
Add 35 + 10 = 45
45 + 6 = 51
Q6. Lily Elizabeth has 32 jade stones and 19 ruby stones. How many stones does she have now? Use a number line and add the numbers.
19 has 1ten 9 ones.
32 + 10 = 42
42+9 = 51
Exercise
A. Find each sum. Solve any way you choose. Draw or explain what you did.
- 37 + 10 = _____
- 69 + 8 = _____
- 50 + 32 = _____
- 72 + 19 = _____
- 12 + 28 = ______.
- A baker sells 35 banana muffins and 29 oat muffins. How many muffins did he sell in all?
- Jason has 24 waistcoat and 12 trousers. How many outfits he has now?
- There are 52 birds and 47 animals in the zoo. How many birds and animals are there in total?
- Sam wants to make a necklace. She used 26 pearls and 37 corals. How many beads did she use in all?
- Find the equation the model shows.
Concept Map:
What We Have Learned
- Solve addition problems using different strategies.
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