Task 8

Materials and tools for a working group:

containers of various shapes, measuring cup (measuring cylinder)

The aim of this task will be to investigate what happens to the water in the container when exposed to sunlight. The teacher can start the activity by forgetting the water in the glass on the balcony. The next day he found only an empty cup. He discusses with pupils what could happen with water and whether they have similar experience (e.g. puddles after rain, water in the children‘s pool in the garden, etc.). In the discussion they come to the concept of evaporation.

Further, they are asked if they think it is important in which container the water is located - cups of different shapes, all of the same material, with the same volume of water and placed in the same place. Pupils write down their predictions. The teacher is again discussing their predictions with them, requesting justification. In the next step, it will ask pupils to suggest how they can verify their predictions. The proposal is more or less resulting our of the assignment. The teacher leads pupils to plan an objective procedure, i. to realize the importance of maintaining a level playing field for all containers under investigation - the same amount of water and the same location.

Pour the same amount of water into the plastic/glass containers (approx. 2 dcl). The water level in the cups is marked with a black marker. Subsequently, the containers are placed in the same place, e.g. on the windowsill. Cups watch in 5–7 days. On the last day they measure the amount of residual water using a measuring cup and compare it with the original amount of water. Thus, pupils will find that the rate of evaporation of water depends on the surface area of the surface, i.e. the larger the surface, the faster the evaporation will take place.

Pour the same amount of water into the plastic/glass containers (approx. 2 dcl). The water level in the cups is marked with a black marker. Subsequently, the containers are placed in the same place, e.g. on the windowsill. Cups watch in 5–7 days. On the last day they measure the amount of residual water using a measuring cup and compare it with the original amount of water. Thus, pupils will find that the rate of evaporation of water depends on the surface area of the surface, i.e. the larger the surface, the faster the evaporation will take place.