Odd or Even
Determine whether a group of objects (up to 20) has an odd or even number of members
What a learner can do afterwards
- Pair objects and determine whether there is one left over (odd) or not (even)
- Count a group by 2s to determine if the total is even
- Write an equation to express an even number as a sum of two equal addends (e.g. 8 = 4 + 4)
1 · Read
A group of things is even if you can put it into pairs with none left over. It is odd if one thing is left over with no partner.
Zoe has 10 buttons. She pairs them up: 2, 4, 6, 8, 10. Every button has a partner, so 10 is even. She can also write it as 5 + 5.
Fast check: count by 2s. If you land exactly on the total, it is even. If you have one left over at the end, it is odd.
Even means everything has a pair. Odd means one thing is left alone.
More to read
Properties of addition
Adding pairs is the start of spotting odd and even numbers. An even number splits into two equal whole groups with nothing left over. The number 8 splits into 4 and 4.
An odd number always has one left over after pairing. The number 9 splits into 4 and 4 with 1 left. That leftover of 1 is the mark of every odd number.
Place-value patterns
Counting by 2s is a fast test for even numbers. Say 2, 4, 6, 8 and keep going. Every number you land on is even.
If you count by 2s and skip over a number, that number is odd. The numbers 3, 5 and 7 never appear in the 2s count.
1.3: Topic C- Place Value
Place value tells you what each digit is worth, and the ones digit settles odd or even. If the ones digit is 0, 2, 4, 6 or 8, the whole number is even.
If the ones digit is 1, 3, 5, 7 or 9, the whole number is odd. Bigger places like tens and hundreds never change this.
Generate patterns
Writing an even number as two equal parts added together proves it is even. The sum 6 + 6 = 12 shows 12 is even. The sum 5 + 5 = 10 shows 10 is even.
Odd numbers refuse to split this way with whole numbers. Try 11: the closest you get is 5 + 6, which is not equal.
Explore more
2 · Watch
به انگلیسیTake it off screen
Where it sits
Optional connections
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.