The similar-triangle proof sheets hide one reason and let a child choose it; this is the next step, where the table is empty and the whole argument is theirs to write. A diagram, a Given, a Prove — and room to build a similarity proof from nothing.
If they get stuck
The answer key prints on a separate page.
Where the congruence version of this sheet finishes on SSS, SAS, ASA or AAS, this one ends on the similarity rules: AA, SAS~ or SSS~. Most arguments start from a line drawn parallel to one side of a triangle, which hands a child Corresponding or Alternate Interior Angles, and two equal angles are enough — that is AA. The Reflexive Property supplies the angle a nested triangle shares with the whole.
This is a written worksheet, not an online exercise, for the reason every proof sheet is: a proof has many valid orderings and wordings, so it cannot mark itself. The answer key is the model — every statement and the reason it rests on, written out in full — which is exactly what a child checks their own argument against.
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Write a similarity proof, step by step