Cover lesson · Integrated Science · Year 10 · Intermediate
LNF: Numeracy → Understanding the number system helps us to represent and compare relationships between numbers and quantities → Financial literacy
Name: Class: Date:
What this practises: numeracy with money in Integrated Science. Pupils convert watts to kilowatts and minutes to hours, calculate energy in kWh and its cost, then work out payback times for LED bulbs and an electric car and judge whether each change is worth it. This is GCSE Integrated Science (Single Award) Unit 1, Section 1.3.1b: learners “use data to determine the payback time of electrical appliances, including electric vehicles”. It is examination content, not NEA.
Print: this sheet, one per pupil, and the stimulus sheet “The Price family energy pack”, one between two. Calculators are needed. No computers are needed.
Run: 6 min read the pack and do Step 1 · 14 min Step 2, the four appliances · 10 min Step 3, LED bulbs · 15 min Step 4, the electric car · 7 min Step 5, advice for Carys · 3 min success criteria. Total 55 minutes.
Collect: this sheet. The worked example has every answer. Checkpoints: the shower costs £7.88 a week; the LED bulbs pay back in about 64 days; the car pays back in 11.5 years at the standard price and 6.5 years at the night-time price.
Carys Price wants to know where her electricity is going and whether two changes would save money. You will use the equations in section 2 of the pack. Write the equation, put the numbers in, then give the answer with its unit. That is how the marks are given in the GCSE examination.
| Appliance | Power in kW (÷ 1,000) | Time each day in hours |
|---|---|---|
| Kettle | ||
| Games console | ||
| Phone charger | ||
| Electric shower |
Use the standard price, 25p per kWh. There are 7 days in a week.
| Appliance | kWh each day (kW × hours) | kWh each week | Cost each week | Rank (1 = most) |
|---|---|---|---|---|
| Kettle | ||||
| Games console | ||||
| Phone charger | ||||
| Electric shower | ||||
| Total |
(b) The kettle’s power is 20 times the games console’s power, but its weekly cost is not 20 times bigger. Explain why, using the equation.
Use section 5.
(a) How many watts does one LED save compared with one halogen bulb? Change it to kW.
(b) How many kWh do all 10 LEDs save in one day? In one year?
(c) How much money is saved in one year?
(d) What do the 10 LEDs cost? Work out the payback time in years, then change it to days.
Use section 6.
| Calculation | Working | Answer |
|---|---|---|
| (a) Petrol cost for 8,000 miles | ||
| (b) Electricity used by the electric car for 8,000 miles | ||
| (c) Cost of that electricity at the standard price | ||
| (d) Money saved each year at the standard price | ||
| (e) Payback time at the standard price (1 decimal place) | ||
| (f) Cost of the electricity at the night-time price | ||
| (g) Money saved each year at the night-time price | ||
| (h) Payback time at the night-time price (1 decimal place) |
Write Carys a short answer of about 80 words. Say which change pays back faster, by how much, and what she should do. Use at least two numbers from your working. Then name one thing from section 7 that could make your payback time for the car wrong, and say whether it would make it longer or shorter.