A child aged 9-10 will be reading timetables and timelines. He will be able to convert units of time from 60 seconds into 1minute, 60 minutes = 1 hour, 24 hours = 1 day.  
Children will also be learning that in digital terms 15 represents a quarter past, 30 equals half past and 45 represents a quarter to. Children should now be able to read time in one minute intervals.
It's important that these skills are encouraged by getting children to read and interpret timetables. During holidays, encourage your child to read the TV guide and ask him when a movie starts and finishes, ask him to help program the DVD recorder. 
Another interesting way of looking at time is to use old family photographs to piece together a family tree across the generations.
Read more about telling time for 11-12 year olds here.