You'll need to do this project on a sunny day. Get a wooden stick, about a meter long, and put it in a place that will be sunny all day, like a south-facing windowsill or the middle of your yard.
At the midpoint of the wooden stick, put another stick standing upright. A regular pencil will be fine. If you're doing this in the yard, you can just jam the pencil in the ground. Inside your house, use tape or clay to get it to stand up.
At 8 am, look for where the shadow of the standing stick hits your long stick. Make a line there (you can carve it with a knife, or just draw it with a pencil or a piece of charcoal.). Come back at 10 am and make a second line. Make a line at noon (at noon there probably won't be much shadow), and at 2 pm, and 4 pm, until it gets dark. Now you have a sundial.
Leave your sundial right where it is, and see if you can tell what time it is the next day without looking at the clock, just using your sundial. How close can you get?
Science in Ancient India, by Melissa Stewart (2002). Written for kids.
Eyewitness India, by Manini Chatterjee (2002). Written for kids.
Ancient India, by Virginia Schomp (2005). Written for teens. Very good for reports.