Teaching sequence

Lesson objective

Students understand that matter can be changed from one state to another by adding or removing heat.

Introduction

Give students an ice cube each and ask them to change it from a solid to a liquid as quickly as they can. Record different methods used and then ask students the following questions.

• What did your methods have in common?
• What other solids can be changed to liquids? What needs to happen to make this happen?
• What needs to be done to turn the liquid back into a solid?
• How could we change the liquid to a gas?

Ask students to consider what processes need to occur to change something from a liquid to a solid to a gas, and back again.

Introduce students to the words ‘melt’, ‘freeze’, ‘evaporate’ and ‘condense’. Can they use these words correctly?

Organise students into cooperative learning teams and provide each team with a copy of the worksheet States of matter (Word 441 KB), a sheet of A3 paper, glue and scissors and the time necessary to complete the worksheet.

When students have completed the task meet together as a class to share the diagrams they have constructed.

Core

Teacher note: The investigation procedure for the following activity can be found in Background information (PDF, 494 KB).

1. Explain to the students that they are going to conduct an investigation on how substances change when heated and cooled.
2. Organise students into cooperative learning teams and provide each student with a copy of the Investigation planner (Word, 392 KB).
3. Introduce students to the liquids that will be used and the equipment that is available. Ask them to read the investigation question – How do substances change when heated and cooled? – and discuss what they think the question means. Ask students to suggest how they might go about setting up an investigation to answer the question.
4. Ask the students to consider and discuss the following questions.
   • How can you ensure that the investigation is fair?
   • What variables will need to be controlled?
   • What variable is being changed?
   • What will be measured and collected?
   • How can the data collected by the class be compared fairly?
   • How can you keep yourself and others safe during this investigation?
5. As a class, develop a procedure to investigate the question. Record the procedure in the appropriate space on the planner (or develop a class copy and provide one for each student). Provide time for students to complete questions 3, 4 and 5 of the investigation planner.
6. Set up a class recording system so that students can add their data to the class data set.
7. Provide time for the students to complete the investigation, recording the data as they go.

Conclusion

Once students have collected and recorded the necessary data and observations from the investigation, meet together as a class to discuss how this data can best be represented. Ask the students if the information can be graphed and what type of graph would be best.

Ask students to look at the data they collected and respond to the following questions.

• Can any conclusions be drawn?
• Was there anything that surprised you?
• How does the data relate to your earlier predictions?
• Is there anything that could be done to improve the data collection?

Provide time for the students to complete questions 6, 7 and 8 of the investigation planner.