Early MathReading hops on a number line to 20
Follow the hops and write the number they land on.
Counting on two to add two is the first time counting becomes arithmetic. These free printable worksheets draw the hop on a number line and ask a child where it lands — forwards for adding, backwards for taking away.
If they get stuck

The answer key prints on a separate page.
Every question is one hop over a 0-to-20 line. The arrow points the way it went, so a backwards hop is a subtraction and the child can see that taking away and counting back are the same move — which is the thing a vertical sum never shows.
The sum itself is not printed, and that is the question. A child who can read 12 − 5 off the arc has related the counting to the arithmetic; printing it beside the line would let them ignore the picture entirely.