Angles in parallel linesEvery angle pair
The two lines are parallel. Find x — check which pair of angles it is.
A line crossing two parallel lines makes eight angles, and only a few of them are different. These free printable worksheets ask which pair the marked angles are.
If they get stuck

The answer key prints on a separate page.
Two of the three facts here give an answer that is already printed on the figure. Corresponding angles are equal and alternate angles are equal, so x is the number the child was given. That looks like a question with nothing in it and is the opposite: a child who cannot see which pair it is has no way to produce that number, and a child who can is finished. Reading the picture is the whole of this standard.
Co-interior angles are the exception and belong on every mixed sheet for that reason. They are the one pair that is not equal — they add to 180° — so a sheet of only the first two teaches "find the matching angle and copy it", which fails on the first co-interior pair a test prints.
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Angles in parallel lines, step by step