Sand timers are useful as a visual representation of a finite period of time. Sometimes there are moments when we simply can't continue following the child's uninterrupted repetitions of activity because there is a transition that needs to be made or an appointment to be kept. If your child, or your class, struggles to accept verbal reminders (such as "we need to go in one minute!" or "one more turn then you need to stop!") then the timer be used as a definitive external reminder - "When the timer runs out it is time to go"! The presence of three separate times (5 minutes, 3 and 1) can help to reinforce this by showing milestones along the way.
The 3-in-1 Sand Timer can also be very useful for cooking as you can keep track of three separate ingredients that are cooking simultaneously (such as when making a bacon, eggs and toast breakfast).
I have also used timers to represent a period of time for our 'Silence Game'. This game involves inviting children to create a 'Silence' by ensuring that their voices and bodies make absolutely no sound at all. The period for this game can be defined in a number of ways - for example, I often use my fingers to count out 10 seconds of silence or we switch the lights off at the start of the silence and only turn them back on when the silence is finished. My class has also enjoyed using sand timers for this game - we create a silence for as long as it takes for the timer to run out! The 1 minute option in this timer would, in my opinion, be the only realistic timeframe for a pre-school class to hold a silence. Even then it would be a significant challenge, as most pre-school age children do not have the self-control to maintain silence for this length of time and it would therefore step into the territory of an artificially 'imposed' silence rather than a fun group project. The 3-in-1 Timer could, however, be part of a 'silence' in a primary school classroom or in a home where just a couple of siblings could work together to maintain a special 'silence'.