Teaching Sequence

Work through this resource material in the following sequence:

20 minutes

Tune in: What will change?

20 minutes

Find out: Experiment time!

20 minutes

Reflection: What did we learn?

Tune in: What will change?

Step 1.

Discuss with students whether some colours can be 'warmer' than others.

They might want to talk about how yellow is considered a 'warm' colour due to their learnings from their art teacher, or how red is often used to indicate fire, which is 'hot'.

If this happens, it might be useful to turn the conversation towards cars and/or houses. Are there any colours of paint that might cause the car to heat up quicker than others if they're left out in the sun?

Step 2.

Explain the experiment to your students.

Step 3.

Students write their predictions in the first section of the Student Worksheet.

Find out: Experiment time!

Step 1.

Wrap one glass with white paper and the other glass with black paper, and secure both pieces of paper with a rubber band.

Step 2.

Fill the glasses with the same amount of water.

Step 3.

Place the glasses in direct sunlight.

Step 4.

Wait a couple of hours.

Step 5.

Measure the temperatures of the water in both glasses with your thermometer.

Reflection: What did we learn?

You know how when we look at a rainbow, we can see lots of different colours like red, orange, yellow, green, blue, indigo, and violet? Well, those colours are all part of the light wavelength spectrum!

Light is made up of tiny particles called photons, and each colour in the light wavelength spectrum is made up of photons with a different amount of energy. Red light has the least amount of energy, while violet light has the most.

The sun emits energy in the form of electromagnetic waves.

When light falls on an object, some wavelengths of light are absorbed by the object, and the rest are reflected.

Darker colours absorb more sunlight than lighter colours because they contain pigments that absorb a wider range of colours from the visible light spectrum.

A black object appears black because it absorbs all wavelengths of light and reflects none of them.

On the other hand, lighter colours reflect more light because they contain pigments that are less effective at absorbing light. When light falls on a light-coloured object, most of the wavelengths of light are reflected back, and very little is absorbed.

The energy from the absorbed light is converted into heat, which is why black objects tend to feel warmer than light-coloured objects in sunlight.

So, the glass of water surrounded by the black paper should be hotter than the other glass of water.

Which Colours are Hotter?

Go to

Summary

Lesson guides and printables

In this lesson