Diving into Mastery Guidance for Educators
Each activity sheet is split into three sections, diving, deeper and deepest, which are represented by the following icons:
These carefully designed activities take your children through a learning journey, initially ensuring they are fluent with the key concept being taught; then applying this to a range of reasoning and problem-solving activities.
These sheets might not necessarily be used in a linear way. Some children might begin at the ‘Deeper’ section and in fact, others may ‘dive straight in’ to the ‘Deepest’ section if they have already mastered the skill and are applying this to show their depth of understanding.
Diving
Deeper
Deepest
Aim
Diving
Checking Strategies
Check these calculations using the inverse operation. Correct any mistakes.
3521 + 4973 = 8495
6735 – 4352 = 2383
Diving
Checking Strategies
3521 + 4973 = 8495
| 8 | 4 | 9 | 5 |
− | 3 | 5 | 2 | 1 |
| | | | |
If the original calculation is correct, the answer should be 4973.
4
9
7
4
7
1
The original answer is wrong. We need to adjust it by taking off 1. The correct answer should be 8494.
8495 - 4973
What other subtraction could we have done to check the answer?
Diving
Checking Strategies
6735 – 4352 = 2383
| 4 | 3 | 5 | 2 |
+ | 2 | 3 | 8 | 3 |
| | | | |
| | | | |
If the original calculation is correct, the answer should be 6735.
6
7
3
5
The original answer is correct.
1
Write 8 calculations you can make using these cards:
4893
1598
6491
+
–
=
Diving
Checking Strategies
4893
1598
6491
+
=
1598
+
4893
=
6491
6491
=
4893
+
1598
6491
=
1598
+
4893
6491
–
4893
=
1598
6491
–
1598
=
4893
4893
=
6491
–
1598
1598
=
6491
–
4893
1598 + 4893 = 6491
6491 = 4893 + 1598
6491 = 1598 + 4893
6491 – 4893 = 1598
6491 – 1598 = 4893
4893 = 6491 – 1598
1598 = 6491 – 4893
4893 + 1598 = 6491
Checking Strategies
Deeper
To check his answer, he did this subtraction:
Raj did this calculation:
5247 + 2358 = 7606
5247 - 2358 =
| | | | |
| 7 | 6 | 0 | 6 |
- | 5 | 2 | 4 | 7 |
| | | | |
5
9
1
1
If the original calculation is correct, the answer should be 2358.
2
3
5
9
The original answer is wrong. Raj needs to adjust it by taking off 1. The correct answer should be 7605.
| | | | |
| 7 | 6 | 0 | 6 |
- | 2 | 3 | 5 | 8 |
| 5 | 2 | 4 | 8 |
Raj could also have used this subtraction to check his answer:
Checking Strategies
Deeper
The class are calculating 8541 – 5544. They all get 2997 as their answer.
Amelia is wrong. She has made a mistake and written 2979 instead of 2997.
Raj is wrong. He has added the wrong numbers. He should have calculated 5544 + 2997 or 2997 + 5544.
Harpritt is correct. 5544 + 2997 = 8541 would be one of the inverse calculations. The other would be 2997 + 5544 = 8541.
Raj says, �“The inverse is
5544 + 8541 = 2997.”
Amelia says, �“We need to calculate
5544 + 2979 = 8541.”
Harpritt says,�“The corresponding addition calculation is � 5544 + 2997 = 8541.”
They check their answers using the inverse.
Who do you agree with? Explain your answer.
Checking Strategies
Deepest
Fill in the missing numbers in the number pyramid.
Two adjacent numbers (numbers which are side by side) add together to give the number above.
Use the inverse to help you get started.
772
125
548
1967
1195
647
Checking Strategies
Deepest
Choose 4-digit numbers to complete these bar models. Find 2 different ways for each bar model. The bar models are not drawn to scale.
These answers are �one possible solution. The 2 blank parts need to add up to 2753 in the top bar model and 2980 in the bottom one.
4000 | ||
1247 | | |
4000 | ||
| 1020 | |
1500
1253
1900
1080
Dive in by completing your own activity!
Checking Strategies
For more planning resources to support this aim, click here.
Twinkl PlanIt is our award-winning scheme of work �with over 4000 resources.
Need Planning to Complement this Resource?
Estimate and use inverse operations to check answers �to a calculation.
National Curriculum Aim