Is 30 odd or even? A worksheet for the ones-digit rule

"Is 30 odd or even?" "Odd, because 3 is odd." That came from a bright six-year-old who could count by twos to a hundred. Odd and even feels like something kids absorb, and for small numbers they do. The rule about the ones digit is a separate thing, and it needs numbers big enough to break the guessing.

What the sheet looks like

The odd and even generator prints a set of numbers and one of four activities: circle the even numbers, circle the odd numbers, write odd or even beside each one, or sort them into two labeled columns. The range runs from 0–20 for kindergarten through 0–50 and 0–100 for first and second grade, then 2-digit and 3-digit for the ones-digit rule. Pages hold 12 to 30 numbers, with an optional answer key.

Why it works

• The ones-digit rule only becomes a rule once the child has met 30, 41 and 108. The 2-digit and 3-digit ranges are the test of whether they have it or are still counting.
• Sorting into columns is slow, and every number gets its own decision. Circling is quick and good for review once the idea is there.
• Zero is in the 0–20 range. "Is zero even" is a good conversation to have at the kitchen table before someone has it at school.

Who it suits

Kindergartners circle the evens in 0–20 and that is enough. Second graders sort 3-digit numbers, which is a two-minute job if they have the rule and impossible if they do not. The skip counting sheet by twos is the natural companion, and the hundreds chart with the evens colored in shows the stripes that make the pattern obvious.

House numbers on a walk are the follow-up. One side of the street is all odd.