What safe, visible kinetics experiments reveal concentration and temp effects?

[Ava16]

I'm a high school chemistry teacher trying to design a new, engaging lab on reaction kinetics that is safe, visually demonstrative, and suitable for a class with limited fume hood access. I want to move beyond the classic iodine clock reaction. For other educators or hobbyists, what are your favorite chemistry experiments for illustrating how concentration and temperature affect reaction rate? I'm looking for reactions that produce a clear color change or gas evolution, use common and low-hazard chemicals, and can be completed within a standard class period. How do you structure the student analysis to connect the observable data to the underlying theory, and what safety precautions are absolutely non-negotiable for you in a classroom setting?

[Paul86]

Three safe, classroom-friendly kinetics demos you can run in a standard period:
1) Acid–base clock in disguise: Use baking soda and dilute acetic acid with a small amount of phenolphthalein in a tall beaker. As the acid neutralizes the base, the solution stays pink until the end when it turns clear. You’ll measure rate by how fast the pink color fades. Vary concentration by changing amounts of vinegar and baking soda; test at 20°C, 25°C, and 35°C to see temperature effects. Have students plot the time to color change versus concentration and extract a simple rate from the slope.
2) Gas evolution kinetics with vinegar and baking soda (colored gas): Put 1–2 mL vinegar with a bit of food coloring in a bottle, fit a balloon over the neck, and add a measuring cylinder to collect displaced water. Vary reagent amounts to see changes in the gas-formation rate. Repeat at different temperatures (ice bath, room temp, warm water bath). Students log volume of CO2 vs time and compare across conditions.
3) Hydrogen peroxide decomposition with yeast (catalase, safe and dramatic): In small test tubes, mix 3% H2O2 with a dash of dish soap and a pinch of food coloring for visibility, then add a small amount of yeast suspension. Use a balloon to capture the produced oxygen or measure the foam height. Vary H2O2 concentration and yeast amount, and run at several temperatures. Students graph the rate (volume/height per second) against concentration and temperature. Important: keep containers small, wear splash goggles, and dispose of peroxide waste according to your school’s guidelines.