Activities
- Warm-up: Review grouping by tens.
- Using grouping by tens, identify the quantity, say, forty-three with 4 tens and 3 ones. Write the quantity as 43. Do the same with forty-two and forty-one, writing them as 4 tens 2 ones and 4 tens 1 one, and also as 42 and 41, respectively. Continuing in this manner, 4 tens should be written as 40. Note that we shouldn’t write 410. Do more examples as necessary.
- Practice converting the expressions such as 4 tens and 3 ones into $40+3$.
- Practice the decomposition of the type $43=40+3$. Try writing $40+3=43$ too.