In this activity, students watch a demonstration and manipulate molecular models. They answer questions to probe their misconceptions and to develop scientific understanding about what happens when a substance changes state.
Students will be able to explain that:
Sequence of activities
Assessment for learning commentary
Discussing personal viewpoints with others allows students to review each other and feed back. Reaching consensus in groups stimulates this process.
The teacher-led plenary discussions help students whose thinking has not moved forward and gives the teacher an opportunity to assess the extent of any misconceptions in the class. Checking the written feedback on worksheets also gives an opportunity to deal with misconceptions as well as confirming correct thinking.
For each student
For the first demonstration
For the second demonstration
Note on the first demonstration
Boil the water in one beaker. Place the water molecule models in the second beaker, to use in explaining the state change.
It is the responsibility of the teacher to carry out appropriate risk assessments for the demonstrations.
What is in the bubbles when water boils?
The bubbles contain a mixture of hydrogen and oxygen.
The bubbles contain carbon dioxide.
The bubbles contain steam (water vapour).
The bubbles are empty (vacuum).
The bubbles contain air.
The bubbles contain oxygen only.
The initial small bubbles, seen as water heats up, contain oxygen.
What happens when ice melts?
The molecules in ice get smaller because water takes up less space
The molecules in ice get warmer because the water is hotter than
The molecules move around more as water than they did in the ice.
Ice molecules change to water molecules.
Ice changes to water at 0 °C.
Ice only melts above its melting temperature.
V. Kind, Changing matter, Ed. Chem. July 2001, 92.