Need help on rock/soil/plants/water project.

So I am doing a 30 minute presentation in 2 weeks and I am supposed to create like a little lesson or activity (pretending to be a teacher teaching 3rd grade students) how rock, water, plants, and soil provide many resources including food, fuel, and building materials that humans use. I thought about it so much and I can’t think of a 20-25 minute activity/lesson to be teaching to pretend-to-be-3rd grade students. This is a project for my class and we are in a group and each individual is supposed to teach to their group.
Just give me like any tips or help on what I should do for a 3rd grade standard.. If I should buy some materials I am thinking to spend only up to 10 dollars. Thanks
Answer #1
The following links might give you some ideas. Just a few activities and lesson plans:
http://www.teach-nology.com/teachers/lesson_plans/science/earth_sciences/rocks/
http://www.sciencenetlinks.com/lessons.cfm?DocID=365
http://atozteacherstuff.com/pages/298.shtml
http://www.brainpopjr.com/science/land/soil/grownups.weml
I would suggest you read about rocks, plants, soil, and find out what they’re all about. Don’t go through them all at once though, you’ll just get confused. Take baby steps for each category and you’ll get through it. Write it down if you have to, it’s good for the memory. Then compile it and follow up on some of the links that I’ve provided. Good luck
Answer #2
Read Geology books. Will be a total help because they’re all related to Geology.
Answer #3
Egypt
they were the 1st to do building (pyramids & cities) & large scale farming
sneak a lil history in there in there and you might impress teacher