Here are 10 classroom STEM projects that require minimal materials:

1. Straw Bridges: Using only straws and tape, students can construct bridges to test their weight-bearing capabilities.
2. Paper Airplanes: Students can experiment with different types of paper and folding techniques to create the most aerodynamic paper airplane.
3. Balloon Rocket: Using a balloon, string, and straws, students can create a mini rocket to explore the concept of propulsion.
4. Egg Drop: Using only a few sheets of paper, students can design a protective casing for an egg to prevent it from breaking when dropped from a height.
5. Catapults: Using popsicle sticks, rubber bands, and a plastic spoon, students can construct a simple catapult to launch small objects.
6. Marble Run: Using cardboard tubes, students can construct a maze-like structure for marbles to roll through.
7. Paper Rollercoasters: Students can use paper and tape to create their own rollercoaster designs to test the laws of motion.
8. Build a Tower: Students can use toothpicks and marshmallows to create the tallest tower possible.
9. Magnet Maze: Using a magnet and a paper clip, students can navigate a maze made out of paper.
10. Solar Oven: Using a pizza box, aluminum foil, and plastic wrap, students can create a solar oven to cook food using the power of the sun.