One effective and fun biology demonstration you can complete with your middle school class investigates the strength of eggshells. Introduce the topic to your students, informing them that eggs require strength to protect the chicks growing within. To prepare for the eggshell strength test, lay newspaper or a tarp over the classroom's main bench. Place four bottle caps in a square with a raw egg point-side down in each one. Ask your middle school students what will happen when you add a book or block of wood on top of the square of eggs. Add the weight on top of the eggs, making sure it is evenly distributed. Keep adding books until the eggs eventually break; young scientists will be surprised how much weight it takes to break the shells.
Chemistry is an often hazardous subject, as students are asked to mix chemicals causing sometimes potentially dangerous reactions using complex equipment. Demonstrate how to manage the health and safety elements of an experiment. Fill halfway four glass beakers with different temperatures of water, such as from a freezer, refrigerator, tap and stove top. Use a thermometer to check the starting temperature. Prepare to start a stopwatch as you drop an Alka-Seltzer tablet into each beaker. Observe the beakers and note the time it takes for each tablet to dissolve completely. Instruct students to think about the effect of temperature on reaction time.
Demonstrate physics in the classroom to impress and intrigue your middle school scientists. One example can be leading students to explore and interact with the qualities of static electricity. Instruct your students to stand around a deep sink and start the cold faucet running at a steady stream. Ask a volunteer to inflate a balloon as you explain protons, electrons and attraction and repulsion. Tie the balloon when it is inflated. Ask a student to rub the side of the balloon with a wool cloth, jumper or sock for at least 10 seconds. Take the balloon and hold it within two inches of the water stream; the balloon will attract the water, causing the stream to bend.
Leading a middle school science demonstration gives you an opportunity to teach and reinforce health and safety during experiments. For example, even when you are leading demonstrations yourself, you should still instruct students to put on laboratory coats, safety goggles and, when necessary for chemistry or electrical science experiments, thick rubber gloves. Furthermore, lead your students through an evacuation of the classroom at the start of the school year to ensure they are well acquainted with the fire safety drill.