What is an appliance? What are examples of appliances in school and at home? Our Energy Project in Term 2 began with these questions. In only a few seconds, lots of ideas were generated. TV, freezer, fridge, oven, lights, computer, mobile phone, X-Box, air conditioner, paper shredder . . . Can you come up with any more? Groups went on an electrical appliances hunt around school, listing what they found in specific areas. As we collaborated to define the meaning of the word "appliance", there were some items from the hunt that inspired much debate, such as electrical sockets, battery operated clocks and light switches. We worked towards an understanding that an electrical appliance is a device that is designed to perform a specific function when powered by an electric current.
Using resources currently being piloted by the team behind "I'm a Scientist, get me out of here", children ordered photographs of electrical appliances according to average daily consumption. How would you order the following appliances? (Scroll down to the bottom of the page to see how you got on. We found there were some surprises!)
When we checked the energy used by a CD player with a power meter we found that any action on the player caused an increase in energy usage, e.g. inserting a CD, pressing "play" and turning up the volume. We also discovered that the player used more energy with the CD in place than when the CD was taken out, even if it wasn't playing.
Electricity is measured in Watts. We can use the information to work out how much electricity an appliance uses and how much it costs to run the appliance.
See if you can work out how much it costs to charge a laptop for two hours using this formula:
Laptop (plugged in a charging) uses 40 watts at 12 pence per unit.
40W divided by 1000 = number of kilowatts x 2 (hours) = number of kilowatt hours x 12 pence = total cost.
(Scroll down to the bottom of the page to check your answer.)
As part of Energy Month, during which schools carry out energy saving actions, children conducted a "switch-off" test. They asked all classes to work with the lights off for a period of time. In their following sessions, groups compared the energy report for the test day (Friday 28th November) with the report for the same day in the previous week (Friday 21st November). Can you tell how the lights-off test may have affected the data?
Throughout the project, groups engaged in lively discussions about the negative environmental impact of growing energy use across the world and particularly the role of carbon dioxide. We explored some alternative, renewable sources of energy in development. To introduce issues relating to climate change, children watched an animation created by children in a London primary school. (You can access the film here.) They also learned how a school in Iowa runs entirely on energy from its own wind turbines and makes money from selling excess energy back to the grid! To see the Iowa clip, go to http//video.nationalgeographic.com/video/wind-power.
Children were given the choice of building a wind turbine powerful enough to lift a paper cup to table height or designing an appliance powered by a renewable source of energy, such as wind, water or Sun. The designs will be displayed in rotation on the Eco Noticeboard in the hall.
Perhaps you might be inspired to have a go at building a wind turbine or inventing an appliance that is powered by a renewable source of energy? You can follow the instructions given here for the wind turbine to get you started but you may find yourself adjusting the design as you go along. If you bring in photos of your turbines or environmentally friendly appliances, we can display them on the Eco Noticeboard.
In the last session of the project, groups took part in a solar panel workshop provided by Alan Macnaughton from Oxfordshire Green Schools. Children wired up electrical circuits to power a light, comparing the performance of a battery with solar panels. Despite the overcast conditions, everyone rose to the challenge of powering a buzzer using only solar panels. Groups used their problem solving skills to work out that the buzzer needed more than one solar panel in the circuit. The workshops offered another opportunity to weigh up the advantages and disadvantages of an existing technology versus an alternative, renewable technology and we discussed how Didcot Power Station is involved when batteries are used. At the end of the workshop we were all inspired to learn about some incredible ways that solar technology is being developed in the USA. How about a solar walkway or even motorway made from reinforced glass panels that can bear the weight of a tractor and generate power? Anything is possible!
(Highest to lowest)
Chip fryer: 12.0 KW/h
Washing machine: 1.4 KW/h
Desktop computer (awake): 0.6 KW/h (asleep: 0.1 KW/h)
Ceiling light: 0.2 KW/h
Photocopier (active): 0.2 KW/h (uses more energy on standby: 1.7 KW/h!)
TV (active): 0.1 KW/h