1 - Getting Started ~3 mins
Look at your rubber. About how many centimetres long is it: 2, 5 or 20? Hold your estimate in your head. No rulers yet.
2 - Watch and Notice ~10 mins
An estimate is a careful first guess before the ruler touches the object.
Look at the 1 cm mark on the ruler. Your fingernail tip is about as wide as that mark.
Count imaginary fingernail-widths along the glue stick (about ten) to make your estimate. Then watch the ruler reading and see how close you came. We do the same for the scissors.
3 - Try It Together ~8 mins
Today we estimate first, then measure. Look at the glue stick on the board. Count fingernail-widths in your head and settle on a centimetre guess. Then line up the zero and read the end.
Estimate then measure
4 - Class Challenge ~11 mins
I will hold up a real crayon, then a straw, then a pencil case. Each time, count fingernail-widths and make a silent estimate in centimetres. We only open that object on the board after the estimates are in. Then one of you measures on the board to check how close we were.
Measure to check
5 - Write Your Estimate in Your Copy ~3 mins
From the crayon we just measured, write in your maths copy: my estimate ___ cm, the real length ___ cm.
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