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Sound - How Sound Travels

Objectives

To understand that vibrations cause sounds.

To understand that sound travels because vibrations travel.

To understand which factors cause louder and softer sounds.

Resources

Plastic wrap | Small bowl | Uncooked rice | Metal baking tray | Large spoon | Lined paper

Today's Lesson

Main Activity

This lesson investigates the way in which sound travels; before you begin, you may wish to watch the following video with your student.

If you throw a pebble into a pond, you will notice the ripples spreading outwards from the point where the pebble entered the water. The principle for sound travelling in waves from the source is exactly the same. Sound travels in waves or vibrations; which we cannot see. When these vibrations make contact with our eardrums, we hear the sound. Different vibrations create different sounds.

Watch the video about the Jumping Rice experiment.

Discuss with your child and have a go at the experiment yourself. Predict what will happen if you clap your hands next to the jar. Try it out. Were you correct?

Sounds are made when things vibrate. You usually cannot see vibrations but you can feel them. A vibration is a quick movement (back and forth). Sounds travel because vibrations travel. Discuss why the rice grains in the activity moved.

Next, help your child to conduct the experiments and help them to write up the experiments in the proper, scientific way, dividing the explanation into three sections, plus a diagram (see example below).

The first section is for the ‘Method’, including ‘Apparatus’: essentially a list of instructions, including the equipment used, that someone else could read and follow to repeat the experiment. This section should also include a description of what was done to make the test 'fair'. Help your child if necessary, using questions or phrases such as, “The apparatus I used was…”

The second section is for ‘Results’: a clear, objective description of what was done and observed. Prompt your child to think about all the senses in this section, including any measurements taken. Summarising results in a table or graph is often useful. Again, help your child with questions or phrases such as, “First we/I...”; “Next I...”; “I noticed that…”; “…and that was because…”; and, “Finally…”

The final section is the ‘Conclusions’: what have you learned by doing this and what do the results actually show? It is often useful to compare variables when making a conclusion. For example: ‘The higher the sun in the sky, the shorter the shadow.” “The rougher the surface, the shorter the distance travelled by the car.” “The length of the pendulum made no difference to the time it took to swing.” 

Useful questions or phrases to help your child here could include:

• “I have learnt some new facts…”
• “I also learnt that…”
• “However, the most interesting thing I learnt was…”

Remind your child to include a fully labelled diagram to show how they set up their equipment.

Here is an example of a written-up experiment that your child could use to help with the planning of their writing.

Method

Apparatus:

A teaspoon of bicarbonate of soda was carefully inserted into the balloon and a tablespoon of vinegar poured into the bottle. Taking care not to mix the two chemicals, the balloon was connected to the top of the bottle with the elastic band so that the apparatus was completely sealed. The bicarbonate of soda was then mixed into the vinegar by lifting and shaking the balloon, and the bottle gently shaken.

Results

As soon as the two substances mixed, I noticed that bubbles were observed rising to the surface of the liquid. The gas produced caused the balloon to inflate slightly and I think this was because…

Conclusion

When bicarbonate of soda and vinegar are mixed, they react and create a new substance - carbon dioxide gas. With nowhere to escape to, this gas causes the pressure inside the apparatus to rise, observable by the inflating balloon.

Note: From now on, any experiment carried out on the course should be written up like this example, and it must also include a diagram.

Citations

[1] www.youtube-nocookie.com