Primary 1 · Mathematics
P1 ordinal numbers and position
Ask a P1 child to colour the 4th star and you may get four coloured stars. "4th" and "4" sound almost the same, and a row of toys shows the difference in ten seconds.
- Level
- P1
- Usually taught
- Term 1
- Covers
- 1 concept
What changes at P1
In Primary 1 your child learns the position words first to tenth and how to write them: 1st, 2nd, 3rd, then 4th to 10th. They use them to say where something is in a row: from the left, from the right, before, after or between.
Until now, every number your child met answered "how many?". An ordinal answers "which one?", and in a row of 7 stars only one star is 4th.
The sentence that costs the mark
There are 7 stars in a row. Colour the 4th star.
What the working usually does
colour the 4th:4 of them=4 stars
Hears 4 and colours four stars, counting carefully from the left.
What the question asked
colour the 4th:the one in 4th place=1 star
Says 1st, 2nd, 3rd, 4th along the row and colours only that star.
Both count carefully to 4, and the coloured stars even include the right one. On the page it looks like over-colouring, not a different idea of what "4th" means.
| Group | Detail |
|---|---|
| 1×star (1st), 1×star (2nd), 1×star (3rd), 1×star (4th), 1×star (5th), 1×star (6th), 1×star (7th) |
The same question, worked properly
Find where to start
from the leftThe question does not say, so start from the left. When a question means the other end, it says "from the right".
Say a position for each star
1st, 2nd, 3rd, 4thOne word for each star, pointing as you go, and stop on the star where "4th" lands.
Colour only that star
1 starThis is the step that fails. "4th" names one place in the row, so one star is coloured. Colouring every star up to it turns a position into a count.
How can you tell it has clicked?
Put a few objects in a row and ask for "the 3rd one". Then, separately, ask for "3 of them". If both requests get the same handful, position and quantity are still one idea.
A child who points along the row saying "1st, 2nd, 3rd" and stops on one object has it. Then try "the 3rd from the right", which checks the other thing the papers test: starting from the end the question names.
One thing to try tonight
Line up 6 toys. Ask for "the 3rd toy", then for "3 toys".
If both requests get the same answer, say the positions aloud together, pointing at one toy per word: 1st, 2nd, 3rd. The toy under your finger on "3rd" is the only one the question wants.
What your child will meet in this topic
- Ordinal Numbers
Most Singapore schools introduce this in Term 1, though schools do differ by a term either way. If your child’s school runs a different order, you can set it in the schedule on your dashboard.
What it leads to
Position words come back in P1 questions about letters in a word ("which letter is 2nd?"), where each letter is one place in the row.
They come back in later years too, in questions about trees or posts standing in a line. There, the answer turns on which place is which, not on how many there are.
More in Primary 1
Other topics in the same year, so you can see what sits either side of this one.
See how your child is doing on this topic
StudyLah marks each step separately, so you can see whether it was the setup or the arithmetic that cost the mark.