Starting in preschool, children are taught that plants need soil, water and light to grow. Many will have done projects growing lima beans from seeds and internalized that seeds grow plants. Challenge the students and this notion and show them how to grown plants from cuttings. Simply take cuttings and have the students place them into a pot of dirt, water them, and have the students watch them as they grow. Alternatively, have them place an onion in a glass of water and it will sprout. This satisfies the North Carolina curriculum standard 7.02, determining the factors involved in the growth and survival of organisms.
An easy project for sixth graders is to set up a bird feeder outside of the classroom window and have the students watch for birds. You can set up a poster board near the window with pictures of common local birds and have the students mark each time they see a bird. You can also have students keep journals indicating which birds they've seen and various characteristics of those birds. You can supplement this project with making the bird feeders as a class. This satisfies the North Carolina curriculum requirement 7.01, which relates to the ways organisms interact with one another and non-living objects.
You can make a small model of the water cycle by taking a large, clear bowl and putting a small plastic cup inside of it. Place some water in the bowl without adding it to the cup. Cover the bowl with a piece of plastic wrap and secure the wrap with a large rubber band or some string. Place a small weight on top of the plastic weight, over the plastic cup. Place the bowl on the windowsill and have the students observe what happens to the water. This satisfies North Carolina curriculum requirement 4.01, related to the the cycling of water.
The simplest form of a solar cooker is a dashboard reflector. By folding the panel into a square with the reflective sides facing the interior part of the square, you can focus the heat. In fact, a simple experiment involves folding the reflector into a square, holding the sides and bottom in place with duct tape, and then placing a thermometer at the center of the square. Comparing that temperature with one taken nearby but not in the solar cooker will demonstrate how reflective panels work to focus heat. This satisfies North Carolina curriculum requirement 6.04, which relates to the transfer of heat and energy.