Find the Missing Number — Space — Grade 1

Each row gives a child the start and the finish and asks for the move between: a group of rockets, planets and a star, the number still there, and a blank for how many left. Finding the missing number means connecting subtraction to its inverse — what taken from the group lands on the result. It is real Grade 1 reasoning, and the pictured space things plus within-twenty numbers keep it checkable by counting, so a child can verify the missing part instead of taking it on trust.

Asking for the taken-away amount rather than the result keeps a child from running a page on autopilot — each row needs real thought about the missing middle. That is precisely why change-unknown problems matter at Grade 1, and why keeping them within twenty is important: the thinking is the work, so the numbers stay small enough to verify by counting the space things.

Children who like space 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 thanksgiving, or find the missing number with vegetables. You can also browse every subtraction worksheet or the whole space things collection for grade 1 — each sheet prints cleanly in black and white or plays online for free.