Are you looking for a resource to show your children how to calculate the duration between a start and finish time? Have a look at this Year 2 Find Durations of Time Teaching PowerPoint.
Helpful images show your children how to use a clock face to work out the duration between two times and also how to use a number line. There are questions throughout that you can use for modelling or for checking your children's understanding. The PowerPoint ends with a reasoning and problem-solving question for you to work through together.