1 - Getting Started ~3 mins
Each egg box holds 10 eggs. Here are 3 full boxes. How many eggs is that, without opening a single lid?
2 - Watch and Notice ~8 mins
Look at the units column on each number. Empty every time. A decade number is whole tens only, nothing left over: 30, 50, 80, 90. The 0 holds the empty units place.
3 - Try It Together ~8 mins
Build decade numbers (whole tens, no loose ones): 20, then 40, then 60, then 70. Count 10, 20, 30… as each rod goes down.
Build a decade number
4 - Write the Decades in Your Copy ~2 mins
In your maths copy, or on your decade-number strip, write 10, 20, 30, 40, 50 in one careful line.
5 - Class Challenge ~10 mins
Board challenge! Build 30, then 50, then 80, then 90. Watch the zero in the units column each time. If a loose cube sneaks in, freeze: who can spot it?
Build the decade numbers
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