Find the Missing Number — Reptiles and Amphibians — Grade 1

This sheet asks "how many were taken away?" Each row shows a starting group of frogs, snakes and a turtle and how many remain; the blank is the amount that left. To find it, a child counts on from the result back up to the start, or thinks of the take-away that fits — the first taste of working a subtraction backward. The reptiles keep it concrete, and the numbers stay within twenty, so every missing-number answer is something a Grade 1 child can confirm by counting what is shown.

Change-unknown subtraction builds the idea that start, change, and result are linked — that knowing two of them gives the third. A child who finds the amount removed is reasoning about that relationship, not just performing a take-away, which is exactly the Grade 1 growth this targets. Pictured reptiles and within-twenty numbers keep it concrete.

Children who like reptiles and amphibians take to the puzzle of working backward, and it suits a child ready for a little more than plain take-away. When this feels easy, try find the missing number with shapes, or find the missing number with trees. You can also browse every subtraction worksheet or the whole reptiles collection for grade 1 — each sheet prints cleanly in black and white or plays online for free.