In this lesson students explore conductors and insulators and identify conductors and insulators in familiar contexts. They examine how colours enhance or reduce the transfer of heat and explore whether they absorb or reflect heat.
Review the concepts from Lesson 2 – conduction and convection.
Read/show Letter 3 from apprentice chef Pierre – melting ice-cream.
Explain to students that they will be investigating why Pierre’s spoon was melting the ice-cream.
Inform students that, in order for them to assist Pierre, they need to examine how different materials act when they come in contact with heat.
- Inform students that some materials are considered conductors and others considered insulators, and that they will be exploring materials to understand what these terms mean.
- Conductor activity.
- Put students into groups and distribute 3 spoons (metal, wood and plastic), 3 plastic cups of warm water and a thermometer to each group. Explain to students that they will be testing the 3 spoons made from different materials – plastic, metal, wood.
- Each group measures and records the temperature of the water in each cup before commencing.
- Have students make and record a prediction about which spoon in which cup will have a higher temperature after the activity. This means it will have absorbed more heat energy.
- Instruct the groups to place each of their spoons into a different plastic cup of water for approximately five minutes.
- Ask students to remove each spoon from the water, feel it and record their observations in their science journals.
- Ask each group to measure and record the temperature of the water in each cup after the activity and to make comparisons between the temperatures in each cup.
- Discuss the concept that the spoons were conductors of the heat energy in the water. Define the term ‘conductor’ as a material that transfers heat easily. Ask students to determine which spoon was the more effective conductor.
- Insulator activity.
- Distribute to each group a water bottle filled with iced water. Ask the students to measure and record the temperature of the water.
- Instruct student to hold the bottle in their hands. Remind them that their hands will begin to feel colder the longer they hold the bottle, as the heat is transferred from them to the bottle.
- Ask students to insert the water bottle into the neoprene cooler that you have distributed to each group. Have students hold the neoprene cooler and record their observations.
- Discuss the concept that the cooler was an insulator. Define the term ‘insulator’ as a material that slows or blocks the flow of heat. Ask students to determine if the cooler was an effective insulator. (Identify that the cooler would have stopped the flow of heat from their hands into the water.)
- Explain that, without the cooler, the heat being transferred from their hands and the surrounding air would have eventually caused the water in the bottle to warm up; the cooler slows the process only and insulators also work in the other way, slowing the flow of heat from a hot object to their hands.
- Discuss how an understanding of conductors and insulators might assist Pierre in his cooking. Name some utensils and equipment that could assist Pierre to be safe around hot things in his kitchen, such as using wooden spoons to stir hot liquids and using oven gloves to protect him from heat when picking up hot items.
- Have students write a letter to apprentice chef Pierre explaining why his metal spoon melted the ice-cream so quickly and their recommendations on appropriate utensils and tools for use in the kitchen.
- Ask students to make suggestions about their experiences with colour and heat, such as dark-coloured and light-coloured cars or clothing. Explain that the colour of an object can influence how it absorbs or reflects heat and that some colours absorb heat, whilst others reflect heat.
- Inform students they are going to conduct an activity to determine which colours absorb heat more readily, and which colours reflect heat more readily.
- Heat and colours activity.
- Distribute the worksheet Heat and colour investigation. Read through the instructions to clarify what each group needs to do.
- Distribute the equipment to each group, reminding them to record their observations as they work through the activity. Complete the activity.
- Ask students to share their findings with the class and to identify which colours are better at absorbing heat, and which colours are better at reflecting heat
Review the concepts learnt in the lesson and clarify any new terms. Watch the video Insulator versus conductor and pause it before the answer is seen on the screen.
Ask students to make suggestions about which one they think is the insulator and which is the conductor.
Explain that in the following lesson they will be using the knowledge learnt so far to help solve a problem for apprentice chef Pierre.