Resources: A3 card, bamboo sticks, flower pots, blindfold, tape, a signal generator and the handout.
For this lesson, familiarity with the concept of reflection is important. Students should understand how sound waves can bounce off surfaces and create echoes. They should also know that some animals, such as bats and dolphins, use sound for navigation and locating objects.
Ask the students to suggest ways they could navigate if they couldn't see.
With the students, work through the presentation, answering questions as you go. Introduce the ideas of echolocation and ultrasound and describe how they are used in medicine and animal communication. This would be a good time to complete the audible range task. They should make a note of their audible range and then use the internet to research the audible range of different animals and how they compare to these animals.
Career Film: Crossrail Apprentices: Katie Kelleher, Lifting Technician at Tottenham Court Road station
Expert Film: Watch the Expert Film with zoologist Mike Linley as he tells us how bats use echolocation.
Ask the students to investigate how their ears can hear the direction sound comes from. There are two activities. The first is to have a group of students sit in a circle. One person will be blindfolded in the centre. Take it in turns to make a noise and see if the blindfolded person can point to where the sound is coming from. Alternatively, you could do this as a pair with one person making the noise and moving. Record how accurate the blindfolded person was.
The second activity is to explore how those sounds can echo to us. Find a flat wall - somewhere outside would be good - and stand around 100 strides away from it. One person will clap and the other person will need to listen out for the echo.
Support: Echolocation obstacle course materials can be pre-made and delivered to the classroom, allowing more time for consolidation of learning and reflection. There are also support questions on the worksheet.
Challenge: Ask the students to time how long it takes for the echo to reach them. Alternatively, they could find an outdoor space with more flat surfaces, clap, and then see how many echoes there are.
Review findings from the practical and then complete the questions on the assessment quiz.
Echolocation uses the fact that sound waves travel in straight lines through liquids, solids and gases before bouncing back from objects in the direction of their source.
Mariners use echolocation in several ways. Ships can detect the depth of the ocean beneath them by bouncing a sound wave off the sea bed. Sound travels at a known speed through sea water so the time taken for the sound to return to the ship can give an accurate indication of the ocean depth. The system is so sensitive that fishermen can detect shoals of fish and even an idea of the size of the fish. Submariners rely almost totally on echolocation.
In the natural world, both bats and dolphins have evolved complex echolocation to find their way in the dark and detect food. Both emit high-pitched sounds through the mouth and receive the bounced sounds through their ears (bats) or forehead (dolphins).