Year 2 Maths | Learn, see, try
Year 2 Maths: use tens to make thinking easier
As numbers grow, counting every object becomes hard to track. Tens and ones give children a structure for reading numbers, adding and explaining their thinking. The aim is to connect a written number to a quantity rather than memorise a column procedure too early.
What to notice
In 34, the 3 means three tens, not three individual objects. Bundles of ten sticks and four loose sticks show why the number is thirty-four. A digit changes its value when it moves to a different place.
What to do
Partition each number into tens and ones. Combine the tens and combine the ones, then put those amounts back together. Use bundles, drawings or a number line depending on what helps your child explain the idea.
Why it works
Adding 34 and 12 can be understood as adding thirty and ten, then four and two. These parts account for every object, so recombining them gives the total without counting from one.
Work through an example
Find 34 + 12 using tens and ones.
- 34 contains 3 tens and 4 ones; 12 contains 1 ten and 2 ones.
- Combine the tens: 30 + 10 = 40. Combine the ones: 4 + 2 = 6.
- Forty and six make 46. Check that adding twelve made thirty-four a little larger.
Equal groups lead towards multiplication
Arrange twelve counters as six pairs. Count 2, 4, 6, 8, 10, 12, then describe the same model as six groups of two. Keeping each group equal matters more than introducing a large set of times-table facts at once.
Measure with repeated units
Place equal-sized blocks end to end along a book. Avoid gaps and overlaps, and use the same unit for the whole measurement. Different-sized units can give different counts for the same length, which is a useful idea to discuss.
A common mistake
Writing 312 for three tens and twelve ones joins the written labels instead of combining quantities. Ten of those twelve ones make another ten, leaving two ones: the total is 42.
A strategy to try
Ask for a second representation. A number can be built with objects, drawn in tens and ones or located on a number line. Moving between models helps reveal whether the place-value meaning is secure.
For parents and carers
If exchanging ten ones for a ten is difficult, physically tie ten sticks together. Keep the loose sticks visible. Return to numbers without an exchange before trying addition that crosses a ten.
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