English

Class 4 - Science - Electricity - Week 3

Mrs Harris challenged us to estimate how many atoms we would have to stack on top of one another to make the thickness of a crisp. We were astonished to learn that it would be equivalent to the number of crisps we would have to stack on top of each other to reach the height of Mount Everest!

We then learnt that electrons move slightly all of the time, whether electricity is flowing through a wire or not. When an electric charge is passed through a wire the electrons flow. By passing balls of paper (which represented the electrons) around the circle we were standing in, Mrs Harris acted as the switch and dictated how quickly the electrons were to move i.e. the flow of the current. Under her instruction, the electrons flowed around the circle until the switch was turned off.

Our investigation today involved establishing whether different materials were electrical conductors or insulators. As with any practical investigation, we made predictions based on our prior knowledge and then set up circuits including items such as tin foil, wooden lolly pop sticks, polystyrene, nails and string. Placing one material in the circuit at a time, we watched to see if the bulb lit up, indicating that electricity was flowing around the complete circuit. We knew that this meant the material was an electrical conductor. On the other hand, when the bulb didn’t light up, we established that the material was an insulator.

To conclude the afternoon, Mrs Harris demonstrated how dissolving sodium chloride (salt) in water enables it to conduct electricity. We learnt that pure water contains very few ions, therefore does not conduct electricity well, whereas a salt water solution (also known as brine) does conduct electricity due to the presence of ions in the solution. We were able to see small bubbles in the water next to the electrodes and established that these were chlorine gas. We’re really looking forward to our next lesson!