Teacher and learner guide

1 · Heating: predict the slope

Set the same target for two trials. Compare Low and High heater levels. Which curve is steeper, and which reaches the target sooner?

Record the target, heater level and time before resetting. Water begins at 25 °C.

2 · Transfer: compare both curves

Continue after heating, or use Start transfer at target. The heater is off. Set a bath temperature from 25–100 °C and a water mass from 0.1–1.0 kg, then press Play.

Try a cooler bath, then a hotter bath. Predict the direction of energy transfer before showing the arrows.

Student challenge: keep it a fair test

Does a larger bath mass change the temperature curves? Keep the starting temperatures the same; change only bath mass. Compare both curves at the same elapsed time and explain your observations.

Explain: heat, temperature and surroundings

Thermal energy transfers from hotter to cooler water. Temperature is a measure of how hot an object is; it is not the amount of thermal energy. The beaker and bath also exchange energy with the room, set to 30 °C in this model.

A flattening curve shows a slower temperature change. Similar temperatures reduce net energy transfer between beaker and bath, but energy exchange with the room can continue.

Teacher notes and model limits

This is an idealised model for comparing trends. Its timing and transfer coefficients are not calibrated to a particular classroom apparatus. Heating to a target below 100 °C is not boiling; the model stops at the selected target and does not simulate a latent-heat plateau or evaporation.

The beaker contains 0.10 kg of water. Setting bath mass to 0 kg hides the bath water; use a positive mass for beaker–bath comparisons. Parameters lock after a trial starts. Pause to inspect; Step advances one simulation step; Reset restores the initial setup and clears the graph.

Lesson sequence: predict individually, compare in pairs, then explain with evidence from both curves. Record results before Reset.

● Orange: beaker · ● Blue: water bath · Grey line: room temperature. The written readout identifies each temperature too.