🔢 Fact Family Triangles Add and Subtract

About Fact Family Triangles Add and Subtract

A fact family triangle holds three numbers and four facts. The whole sits at the apex, the two parts at the base, and from that single picture a child can write two additions and two subtractions — which is the moment addition and subtraction stop being two unrelated things to memorise and become one relationship viewed from different sides. Each triangle on this worksheet has one corner left blank for the child to complete, and which corner is blank rotates down the page. That rotation matters: a sheet that always hides the whole would only ever practise adding the two parts, and the two subtraction facts would never be needed. By moving the gap, the page forces all three views of the same family. Every triangle is generated from its two parts, so the whole is always exactly their sum and a mathematically impossible triangle cannot be produced. Six triangles per page with ruled lines beside each for writing the four facts. The number range grows across the five levels. Each level prints as a clean A4 sheet in black and white and downloads with its own separate answer key listing all four facts. Its on-screen twin is Fact Family Triangle Flip.

Common questions

Why does the missing corner move?

A sheet that always hid the whole would only practise adding the parts. Moving the gap forces all three views of the same family.

Can a triangle ever be mathematically wrong?

No. Each one is built from its two parts and the whole is derived, so an inconsistent triangle cannot be generated.

How many triangles are on a page?

Six, each with ruled lines beside it for writing the four facts.

Is an answer key included?

Yes. Every level downloads with a key listing all four facts for every triangle.