Early MathSkip counting by 2s up to 20
Count by 2s. Write the missing number in each row.
Every row counts by two, and the sheet says so at the top. Five numbers in a run with one of the middle three missing, so a child counts on from the left and checks against the number on the right. Free printable sheets, with an answer key.
If they get stuck

The answer key prints on a separate page.
Counting by twos comes in two flavors and this sheet prints both. An even run — 4, 6, 8, 10, 12 — is the one everybody starts with; an odd run — 7, 9, 11, 13, 15 — is the same step landing on the other set of numbers, and a child who has only ever seen the even one often reads it as a different skill. It is not, and putting them on one page is what shows that.
Five numbers, not three. A run of three is a single addition with the answer written twice; five is long enough for the rhythm to be audible, which is the whole point of counting aloud in steps. The blank never sits at either end, so the answer can be reached from the left and confirmed from the right.
6, 8, 10, ?, 14