While the little ones are working on telling time on our analogue clocks today, the older children are learning to tell time the 3rd century BC way, with an astrolabe.
An Astrolabe is a really old, and I mean really old, computer, used for navigation, measurement, and telling time, among other things. Tom Wujec has an excellent video introduction to the astrolabe, here, on YouTube.
Basically, it works by measuring the height, in degrees, of a fixed point in the sky, like a star, or the sun, and then checking against a built in star chart to find the time of day, on the particular date, your fixed point would be at the height you measured. It sounds fairly complicated, but it's actually quite elegant in it's simplicity.
We followed instructions, and used a couple of printouts from the Center for Science Education, to make, and use our own simple astrolabe with tape, string, glue, scissors, thin cardboard, a hole punch, a washer, a mater printout, and a rete/chart printout.
Basically, we glued the mater printout to a piece of thin cardboard...
...cut it out...
...poked a hole through a marked spot, and attached a string, with a washer to weight it down, and taped a piece of a straw onto the top.
Then, we used the device to measure the height of the sun (we let the sunlight tunnel through the straw onto our hands, instead of looking through the straw, directly at the sun).
Finally, we recorded the time we took the measurement, and the height of the sun, on the chart.
Now, tomorrow, if we measure the height of the sun, at the same time, our measurement should be the same as today's.
Obviously, making the first star chart would have been a tedious, detailed work. It's not surprising then, that this particular timepiece was originally made, and used by mathematicians, and astronomers.
It's great to be a homeschooler.