Feb 11

Think 10 and Rebalancing: Making Addition Easier!

This week we have been learning two powerful mental maths strategies to help us add a two-digit number and a one-digit number more easily:

  • Think 10

  • Rebalancing

We used our whiteboards and pens to work through the problems step by step. We also used a part-part-whole model to help us see how numbers can be split and adjusted. These strategies help us solve tricky additions in a smart and efficient way!

⭐ Strategy 1: Think 10

Example: 72 + 9

When we use Think 10, we look for a way to make the next multiple of 10 because adding to a multiple of 10 is much easier.

Step 1: Look at 72

We know that:

  • 72 needs 8 more to make 80.

Step 2: Break apart the 9

Using our part-part-whole model:

  • 9 can be split into 8 and 1

Step 3: Add in parts

  • 72 + 8 = 80

  • 80 + 1 = 81

So,

72 + 9 = 81

By thinking about making 10 (or the next multiple of 10), the calculation becomes much simpler!

⭐ Strategy 2: Rebalancing

Example: 59 + 8

Rebalancing means we add 1 to one number and take 1 away from the other number to make the calculation easier — without changing the total.

Step 1: Look at 59

59 is very close to 60. That makes it a good number to adjust!

Step 2: Move 1

  • Take 1 away from 8 (8 becomes 7)

  • Add 1 to 59 (59 becomes 60)

Now the calculation becomes:

60 + 7

Step 3: Add

60 + 7 = 67

So,

59 + 8 = 67

The total stays the same because we balanced the numbers — we just made it easier to calculate!

🧠 Why These Strategies Help

  • They make mental maths faster.

  • They help us understand how numbers work.

  • They build confidence with bigger numbers.

  • They show that numbers can be flexible!

Using whiteboards helped us try ideas, make changes, and clearly see how part-part-whole modelling works.

🏡 Home Learning Targets

Here are three targets to practise at home:

  1. Use Think 10
    Solve:

    • 64 + 8

    • 73 + 9

  2. Use Rebalancing
    Solve:

    • 48 + 7

    • 69 + 6

  3. Explain Your Thinking
    Choose one question and explain:

    • How did you split the number?

    • Did you make a multiple of 10?

    • How did you rebalance?

Try using a piece of paper to draw a part-part-whole model just like we did in class!