Today is rung 3 of 9 on this topic
Decimals — tenths and hundredths
Can do: Reads, writes, compares and orders decimals, and links 0.5 to 1/2 and 0.25 to 1/4.
Why it matters
Decimals are place value extended right of the point. Children who don't see the connection to fractions treat them as an unrelated second system.
What it looks like when it's wobbly
Thinks 0.45 is bigger than 0.7 because 45 is bigger than 7 — the classic longer-is-bigger error.
⏱️ Two-minute check
"Which is bigger, 0.45 or 0.7? Write 3/4 as a decimal."
Solid looks like: 0.7 with a reason about tenths, and 0.75.
The full activity for this topic · 15 minutes
Money Makes Decimals Obvious
- 1Shade a hundred grid: 0.7 is seventy squares, 0.45 is forty-five. The comparison becomes visible.
- 2Use money: 0.7 of a dollar is 70 cents, 0.45 is 45 cents. Which would you rather have?
- 3Line decimals up by the point, filling gaps with zeros: 0.70 versus 0.45.
- 4Find decimals on a ruler in millimetres.
- 5Convert between the three forms: 1/4, 0.25, 25%.
If it's too hard
Tenths only, with money.
If it's too easy
Order five decimals with different numbers of places, and place them on a number line.
Say this
"Would you rather have 70 cents or 45 cents? Same question — which decimal is bigger?"