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Cotmanhay Junior School

Safe, Happy Learning

Week 6 - 8 Decimals

National curriculum content

  • Recognise and use thousandths and relate them to tenths, hundredths and decimal equivalents
  • Solve problems involving number up to three decimal places
  • Multiply and divide whole numbers and those involving decimals by 10, 100 and 1000


Lesson objectives

  1. Use known facts to add and subtract decimals within 1
  2. Complements to 1
  3. Add and subtract decimals across 1
  4. Adding decimals with the same number of decimal places
  5. Subtracting decimals with the same number of decimal places
  6. Add decimals with different numbers of decimal places
  7. Subtract decimals with different numbers of decimal places
  8.  Efficient strategies for adding and subtracting decimals
  9. Decimal sequences
  10. Multiplying decimals by 10, 100 and 1,000
  11. Dividing decimals by 10, 100 and 1,000
  12. Multiply and divide decimals - missing values


What we want children to know

  • To apply their knowledge of place value to decimals
  • That the decimal point does not move
  • To understand that ten tenths equals 1 whole, 100 hundredths equals one whole and how these relate to each other in the context of calculation
  • How to use place holders in context to support calculation
  • Pupils should go beyond the measurement and money models of decimals, for example, by solving puzzles involving decimals


What skills we want children to develop

Use knowledge to solve reasoning and problem solving questions such as:


Here are four calculations.

Which one is the easiest to answer?

Which one is the trickiest to answer?

Explain your choice of order.

0.45 − 0.3 =

0.45 − 0.15 =

0.45 − 0.23 =

0.45 − 0.18 =


Use this number sentence to write down three more pairs of decimal numbers

that sum to 3:

1·6 + 1·4 = 3


Dexter and Annie have some money.

Dexter has £3.45 more than Annie.

They have £12.45 altogether.

How much money does Annie have? Use a bar model to help.


Mathematical Talk

  • What is the number represented on the place value chart? What digit changes when I add a hundredth?
  • If I’m taking away tenths, which digit will be affected? Is this always the case? How many hundredths can I take away before the tenths place is affected?
  • How would partitioning a number help us? How do you decide what number to partition? Why is partitioning 0.67 into 0.55 and 0.12 more helpful than 0.6 and 0.07?
  • Why is the position of the decimal point important?
  • What happens when you need to subtract a greater digit from a smaller digit e.g. 3 hundredths subtract 4 hundredths?