time uses a range of units and systems. some time units are based on natural events such as the time it takes for the earth to circle the sun. daily time is measured using the 12 hour clock (am and pm) or the 24 hour clock.

Key Skills


  • change between different time units
  • calculate the number of units between two times
  • change between 12 hour clock times and 24 hour clock times


24 hour clock.