Track the Shadow

If it's a sunny Sabbath, find or setup a permanent object which will have a shadow for as much of the day as possible. Then put down a marker every half hour of the day of where the shadow edge/point is up to. By the end of the day you will have an interesting graph.
Alternatively, for a long term experiment, each Sabbath of the year, at exactly the same time (early afternoon), put a marker down. See what shape you end up with once all 52 markers are placed!
There's story in the Bible about the sun's shadow moving strangely...