Want to have your students practice using number lines to add and subtract? These secret code jokes make students excited to practice using a number line to add and subtract. My students loved it so much they asked me if they could take it out to recess with them!! When the students solve the code, they will find a hilarious joke. Answer sheets are also included. This package includes 5 different secret code activity pages. Each page has a variety of addition and subtraction problems. My students used a small eraser (we used ones that were in the shape of a bunny) to actually hop forwards and backwards on the number line.