Cover lesson · Science · Year 8 · Intermediate

Calculating means and anomalies in an insulation investigation

LNF: Numeracy → Understanding the number system helps us to represent and compare relationships between numbers and quantities → Calculation

Also assessed, DCF: Data and computational thinking → Data and information literacy

Name: Class: Date:

Cover teacher: you need no subject knowledge

What this practises: calculating means, ranges and percentage decreases to 1 decimal place after identifying and excluding an anomalous repeat reading (LNF numeracy: calculation), alongside checking data validity and linking results to thermal conduction and trapped air (DCF: data and information literacy).

Board: open the supply teacher presentation (/cover-lesson-resources/presentations/calculating-means-and-anomalies-in-an-insulation-investigation.html) for board slides, countdown timers and a spoken script.

Print: this worksheet, one per pupil, and the stimulus sheet “Testing thermal insulators: Class 8B’s method, repeat readings and physics notes”, one between two. No computers or lab equipment are needed. Pupils need a calculator.

Run: 5 min settling starter · 5 min brief and key vocabulary · 10 min Step 1, variables and the effect of the anomaly · 10 min Step 2 and Step 3, calculating means, ranges and percentage heat loss · 12 min Step 4, writing the structured conclusion · 5 min partner/self check against success criteria · 3 min plenary quick-check. Total 50 minutes.

Collect: this worksheet. Quick checks: anomaly is Beaker D (Bubble wrap) Repeat 3 = 29.0°C (lid left off); Bubble wrap mean with anomaly included is 20.8°C (20.75°C), and excluding anomaly is 18.0°C; valid means are A = 32.0°C, B = 28.0°C, C = 22.0°C, D = 18.0°C, E = 12.0°C; valid ranges are all 1.0°C; percentage heat losses from 80.0°C are A = 40.0%, B = 35.0%, C = 27.5%, D = 22.5%, E = 15.0%.

What you are doing

Class 8B at Ysgol Bryn Celyn tested five 250 cm³ beakers containing 200 cm³ of water starting at 80.0°C to find out which wrapping material is the best thermal insulator over 15 minutes. Using the stimulus sheet, you will identify the variables, prove mathematically why an anomalous reading must be excluded before averaging, calculate the mean temperature drop, range and percentage heat loss for all five beakers, and write a scientific conclusion linking trapped air to thermal conduction.

Step 1: variables and spotting the anomalous reading

Use Sections 1 and 2 of the stimulus sheet.

(a) Complete the variables table for Class 8B’s investigation.

Variable type In Class 8B’s investigation
Independent variable (what was changed between beakers)
Dependent variable (what was measured over 15 minutes, with unit)
Three control variables (kept the same for a fair test, with values)

(b) Look at the four repeats for Beaker D (Bubble wrap) in Section 2: 17.5°C, 18.5°C, 29.0°C, 18.0°C. Identify which repeat is the anomaly and explain the physical reason why leaving the cardboard lid off caused such a large temperature drop.

(c) Calculate the mean temperature drop for Beaker D (Bubble wrap) in two ways to show why anomalies must be excluded before averaging. Show your working.

Wrong method: including all 4 repeats (divide by 4) Correct method: excluding Repeat 3 (divide by 3)

Step 2: calculate the valid mean and range for all 5 beakers

Use the raw readings in Section 2 and the formulas in Section 3 of the stimulus sheet. Show the addition and division for every mean, and give answers to 1 decimal place.

Beaker & material Repeat drops (°C) (circle any anomaly) Working and valid mean drop (°C) Range of valid repeats (°C)
A: No insulation 32.5, 31.5, 32.0, 32.0 128.0 ÷ 4 = 32.0°C 32.5 − 31.5 = 1.0°C
B: Aluminium foil 28.0, 27.5, 28.5, 28.0
C: Corrugated cardboard 22.0, 22.5, 21.5, 22.0
D: Bubble wrap 17.5, 18.5, (29.0), 18.0
E: Sheep’s wool fleece 12.0, 12.5, 11.5, 12.0

Step 3: calculate final temperatures and percentage heat loss

Every beaker started at 80.0°C. Use your valid mean drops from Step 2 to calculate the final temperature after 15 minutes (80.0 − mean drop) and the percentage heat loss ((mean drop ÷ 80.0) × 100). Give percentages to 1 decimal place.

Beaker & material Starting temp (°C) Valid mean drop (°C) Final temp after 15 min (°C) Percentage heat loss from 80.0°C (%)
A: No insulation 80.0 32.0 48.0 (32.0 ÷ 80.0) × 100 = 40.0%
B: Aluminium foil 80.0
C: Corrugated cardboard 80.0
D: Bubble wrap 80.0
E: Sheep’s wool fleece 80.0

Step 4: write a structured scientific conclusion

Use your figures from Steps 2 and 3 and the physics notes in Section 4 of the stimulus sheet to write your conclusion. Follow the 4 prompts on the board: (1) rank the materials with their mean drops and percentages, (2) explain why sheep’s wool fleece and bubble wrap insulated best (trapped air and conduction), (3) explain why aluminium foil performed poorly, and (4) explain the role of Beaker A and how the anomaly was handled.

Step by step

  1. 5 min Settling starter: read Sections 1 and 2 of the stimulus sheet and spot the anomaly in Beaker D.
  2. 5 min Read Sections 3 and 4 of the stimulus sheet and review the five key words.
  3. 10 min Step 1: identify the variables and calculate the Bubble wrap mean with and without the 29.0°C anomaly.
  4. 10 min Step 2 and Step 3: calculate the valid mean, range, final temperature and percentage heat loss for all 5 beakers.
  5. 12 min Step 4: write your 4-part scientific conclusion linking trapped air to thermal conduction.
  6. 5 min Check your worksheet against the success criteria below and tick each box you have met.
  7. 3 min Plenary: check your completed results table against the board before handing in your sheet.

Success criteria

If you finish early