Simultaneous prompting has been effective in teaching a variety of skills, of different levels of complexity, to children with learning difficulties. The current study replicated and extended previous research by teaching three children with Autism to calculate elapsed time. Elapsed time is the duration from a start to end time. When the minutes of the start time are greater than the end time, regrouping is necessary. Simultaneous prompting was used to teach participants to discriminate the type of problem and engage in the respective behavior chain for problems that required (5-step) and did not require (3-step) regrouping. Results demonstrated that all three participants readily acquired the respective behavior chains and were able to accurately report the elapsed time for both types of problems.