Task 1: Change of temperature during vaporization

Topic: properties of substances, temperature measurement

Level: Primary (1.–5. Graders)

Thematic Unit: science

Subject: 6–11 years old or older

Recommended age of pupils: preparation: 15 minutes, implementation: 15 minutes


Time allocated:

For every working group, the teacher prepares 3 thermometers, cotton wool, slide or any unabsorbent mat, three droppers, and storage bottles with water, acetone (nail polish remover), ethanol (alcohol). It is important to have the thermometers and solutions in the storage bottles ready in the classroom at least one hour before the experimental measurement so that they can warm up to the room temperature. Pupils are explained how to read the thermometer values correctly, and are told not to touch the metal tip of the thermometer in order to not distort the measurement results.

Pupils estimates, based on their own experience, what temperatures they are likely to measure after soaking the ball of cotton wool into the solutions. Pupils can discuss it in their groups and come to a common conclusion. If any of the pupils has opposing opinion from the other pupils in the group, he/she explains his/her idea to the classmates and he/she completes the worksheet with his/her own estimate.

Working procedure: The ball of cotton wool attached to the tip of the first thermometer is soaked into water and taken out immediately, in the same way the second ball of cotton wool, attached to the tip of a thermometer is soaked into acetone and the third one is soaked into ethanol. Pupils place the thermometers on the unabsorbent mat. Two minutes later pupils write the read values into the attached table.

If the cotton wool did not cling properly to the tip of the thermometer or was causing problems to pupils when manipulating with it, it is possible to use a rubber band to hold it in place. Eventually the cotton wool can be soaked in the solution and wrapped around the thermometer after that. In that case, it is necessary to use rubber gloves.