A4 laminated decimal point grid that can be written on using dry wipe board markers.
It can be a mine field teaching children the concept of decimals as part of the number system picture e.g. 1 = 1.00, or 1.1 = 1.10. Many children in years 5 and 6 have great difficulty understanding this and in many cases they do not see this unless a pound sign is put in front of the digits. This becomes even clearer when asking them to multiply or divide by 10 or 100; most children will respond that all you need to do is add or remove zeros. So imagine their confusion when you present them with the question 0.01 x 10 or 2.5 x 100?
Do my children think like this?
I quickly realised that children were confused by different methods of teaching, some were taught that the digits moved, others were taught, the decimal point moved; some children were still unsure of their left and right and numbers decreasing when dividing and increasing when being multiplied.
Is the method taught in my school consistent? Is this something I should check out?
What I did:
As part of the starter I used the ‘moving digits’ ITP resource suggested by the National Strategies Primary. This was fine for able children, who quickly grasped the idea of digits moving to the left when being multiplied and right when divided. It didn’t really help the lower attaining children who needed to physically move the digits themselves.
Would the use of ‘moving digits’ help me to explain more clearly?
Each child was given a decimal point board and marker pen. Questions were generated first by myself, then, during paired work, the children generated their own questions using decimal numbered dice, and x and ÷ dice. The generated number would be written on the top row, then multiplied or divided by 10 and 100, making each digit jump in the relevant direction, writing the digits new position on the lines below, e.g. 24.3 x10, 24.3 x 100, 24.3 ÷ 10, 24.3 ÷ 100.
how could I adapt this for my lower attaining children?
Initially, questions would be asked such as will my answer increase/decrease, will my number jump to right/left, how many jumps will my digits make?
Children would use their pens to show the jumps as arrows – just as they would on a number line. To further their understanding play money would also be used to test their answers.
This activity has been very effective in deepening children’s knowledge of right and left and their understanding of what they should look for when self checking their own work e.g. division: their generated number will decrease, multiplication: their generated number will multiply/increase. It also improved their understanding of place value.
Children soon became very fast at calculating divisions and multiples of 10 and began to apply their knowledge in other mathematical areas such as percentages, more complex multiplication and divisions, converting grams and Newtons in science.