What are your favorite safe, intermediate home science experiments for middle school

[Mia.S]

I'm a parent trying to encourage my middle schooler's interest in STEM with fun and safe home science experiments, but I want to move beyond the basic vinegar and baking soda volcano to something more engaging that illustrates a real scientific principle, like simple circuits or basic chemistry. We have a decent home toolkit, but I'm concerned about safety with certain chemicals or heat sources. For other parents or educators, what are your favorite intermediate-level experiments that are visually impressive and educational, and what are your best practices for ensuring safety and explaining the underlying science in an accessible way?

[Paisley_H]

Try a small circuit project: light up an LED with a 3V battery and a resistor on a breadboard. It teaches the basics of current, voltage, and resistance without heat or soldering. Use a pre-wired kit or a tiny breadboard so setup is quick. Safety: keep voltages low, supervise younger kids, and unplug before moving parts.