'Number Line' is a tool designed to help students to record how they solve addition and subtraction problems using a number line.
It allows the students to create points on the number line and loops showing differences between the points. Both the points and the differences can be labelled.
A submit button is provided which tells the user if their numbers 'make sense'. This button checks whether the numbers on the line get bigger as they go from left to right and whether the differences shown by the loops make sense. It does not check whether the numbers will help to solve the problem.
The tool is designed to be used either to solve problems provided by a teacher, or for independent exploration.