I am remaking the ITPs so that they will work on all modern browsers and tablets. They will remain freely available to all without the need for a subscription. This ITP shows how a number line can be developed from a row of 10, 20 or 100 counters. It behaves like a short film. The film is in four stages. You can pause at the end of each stage. The ITP can be used to help children to understand how a number line relates to discrete objects placed in a row, and to support their counting and recording skills. Using the different sequences the number line image can be developed to increase the interval between numbers and to support addition and subtraction activities, moving from the counters to the number line. The ITP can be used to develop children’s estimation skills and their strategies for checking calculations by referring to the 5s and 10s landmark numbers.