Simple Cardboard Sundial

Sundials are a great way to spend a sunny afternoon, especially with kids, teaching them about the earth's orbit. In this instructable, I'll teach you how to make a sundial in just a few steps.

Cardboard circle

Thin dowel

Pocket Knife or saw

Ruler

Pen

Scissors

Compass

Cut out a large circle from cardboard. I just traced a bowl we had lying around the house. This will be your base for the sundial.

Next we're going to make the gnomon, or the stick that casts the shadow. We will take a thin dowel or straw, and cut it so it is shorter. Then, make a hole in the middle of the circle, big enough for the straw or dowel to fit in.

Now we will draw a straight line from our hole to the top of the circle. Next to this write, "12".

Now you can take your sundial outside, at about 11:50 in the morning, and place it in a place that gets sun all day. You can take a compass and find your closest celestial pole, if you are in the Northern Hemisphere, that would be North, and if you are in the Southern Hemisphere, it would be South. Once you find it, tilt the straw or dowel slightly in that direction.

Using a reliable time source, like a phone, when it reaches exactly 12:00 am, rotate the plate so that the shadow cast by the gnomon lands on 12:00. Make sure that the gnomon is still pointing to your closest celestial pole. Use thumb tacks to stick it in the ground so it doesn't move. Now for the rest of the day, every hour, check where the shadow is and make a line with a permanent marker, and write the time. Now you have your very own sundial. Ask your child to tell you what time it says on the dial, and explain to them how it works.