Starter quiz
- Which equation has a whole that is a multiple of 10?
- ______ − 34 = 26 ✓
- ______ − 46 = 55
- ______ − 81 = 18
-
- Which bar model represents the equation shown? 61 = 93 − ?
A ✓
B
C
- Write the addition equation you would use to check this subtraction. 84 − 37 = 47
- '37 + 47 = 84' ✓
- Which number would solve the equation. 54 − ______ = 31
- 85
- 23 ✓
- 32
-
- Which bar model would represent the equation shown? ______ − 14 = 46
A
B ✓
C
- Solve the equation ______ − 27 = 29
- '56' ✓
Exit quiz
- In which of the following equations will you have to bridge 10?
- 34 − 13 = ?
- 56 − 27 = ? ✓
- 83 − 42 = ?
-
- Which of the following equations is correct?
- 32 − 26 = 14
- 84 − 32 = 56
- 93 − 64 = 29 ✓
-
- Solve the following equation. 75 − 47 = ______
- '28' ✓
64 tickets are needed to buy a cap and the unicorn. If the unicorn costs 36 tickets, how much does the cap cost? ______ tickets.- '28' ✓
Izzy had 85 tickets and she bought a pair of sunglasses at the ticket shop. Now, she has 38 tickets left. How much did the sunglasses cost? ______ tickets.- '47' ✓
- Match each equation to the correct answer.
- 69 − 21 = ___⇔48 ✓
- 71 − 39 = ___⇔32 ✓
- 55 − ___ = 27⇔28 ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Some problems involving the subtraction of two-digit numbers, can be solved by bridging 10
- We can look to see if the ones digits cross the tens boundary to find out if we must use the bridge 10 strategy
Common misconception
When subtracting, children may partition the whole and the part, look at the ones digits involved and simply subtract the smaller digit from the larger digit, e.g. solve 75 - 36 as 70 - 30, then 6 - 1
Consider whether or not the equation involved will require the 10 tens boundary to be crossed before solving, referring specifically to subtracting the ones digit from the whole number, e.g. think 75-6 rather than 5 -6
Keywords
Partition - To split a whole up into parts
Part - A piece or section of a whole
Bridge 10 - An addition or subtraction strategy where numbers are partitioned to reach the previous or next multiple of 10, so bonds to 10 can be used to calculate more efficiently.
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