1. Measure 30 cm³ of acid into a polystyrene cup standing in a beaker (so it does not tip).
2. Record the starting temperature.
3. Add the alkali 5 cm³ at a time, stir, and record the highest temperature each time.
4. Carry on past the point where the temperature starts to fall.
5. Repeat and calculate means.

A lid and the polystyrene cut energy transfer to the room, so the measured rise is closer to the true one.

Plot temperature against volume added. The points rise while acid is left, then fall as extra cold alkali is added. Draw a best-fit line through each set: where they cross is the volume that just neutralises the acid, and the highest temperature.

Independent variable: what you change (volume of alkali). Dependent: what you measure (temperature). Control: concentrations, starting temperature, the cup.