The activity Set I am picking is the Sun and Shadows.
I would tell the children that we are going to use the sun and shadows to tell time. Discuss that this is what they used long ago to tell the time before phones/ clocks etc. People long ago used a sundial.
Have any children ever seen a sundial? Do they know how it works? Explain that a sundial has a stick or pointer that makes a shadow. This is called the gnomon. It is important that in the Northern hemisphere the gnomon always points North, or you will not be able to read the sundial. Explain that the Earth turns on its axis. This means that the position of the Sun with regard to the Earth is always changing. Demonstrate this using a torch and an orange. Explain that the shadow of an object also changes as the Earth rotates. The sundial uses this fact. By looking at the position of the shadow of the gnomon on the sundial, you can tell what time it is.
Make a simple sundial with the children- poke a straw through a paper plate and take it outdoors when it’s sunny. Every hour, mark the time of day where the shadow from the straw strikes the plate. Use your sundial to tell the time on the next sunny day.