This mental math interactive worksheet is for students who are starting to learn addition up to 20.

Students have to add the number 1 to the numbers from 0 to 19. For the first task, they have to drag the sum to the corresponding problem, and for the second task, they have to write down the sum.

There is a hidden picture in the background of the problem to further motivate students to solve the problems by adding up to 20.

The performance of each student can be checked during or at the end of the tasks.