Comparing scientific explanations (conflicting viewpoints)

Working scientifically

CCSS NGSS.SEP 7CCSS NGSS.SEP 8England: KS4 Working scientifically

Objective and success criteria

Students will: Comparing scientific explanations (conflicting viewpoints).

I can answer questions on today's skill on my own, without help.
I can explain each step and say why it works.
I can check my answer and spot a mistake.

Before and after

Needs first: Evaluating experiments (research summaries)

Leads to: the next skill in this area.

Materials: Simple equipment for a fair test, Results table template, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

Quick retrieval from earlier learning (Evaluating experiments (research summaries)). Students answer on mini whiteboards.
Show answers together and note who needs support in the main task.

Experiment 1: Magnesium ribbon was added to hydrochloric acid at concentrations of 0.5, 1.0 and 2.0 mol/dm³ at 25 °C, and the gas volume after 1 minute was measured. Experiment 2: The 1.0 mol/dm³ acid was used at 15 °C, 25 °C and 35 °C. In Experiment 2, which variable was changed on purpose? (the colour of the magnesium / the temperature / the volume of gas after 1 minute / the acid concentration) → the temperaturePrompt: Look only at the description of Experiment 2.
Experiment 1: Seeds were kept at 10 °C, 20 °C and 30 °C, all watered daily, and the number that germinated was counted. Experiment 2: Seeds were kept at 20 °C and given 0, 5 or 10 mL of water a day. Which variable was kept constant in Experiment 2 but changed in Experiment 1? (the temperature / the volume of water / the number of seeds that germinated / the colour of the pots) → the temperaturePrompt: What was tested in Experiment 1?
In a drug trial, neither the patients nor the doctors know who gets the real drug. Why? (To save money / Because the drug is secret / To make the trial shorter / To stop expectations from biasing the results) → To stop expectations from biasing the resultsPrompt: People's beliefs can change what they report.

Hook · 6 min

Show a simple experiment with one thing changed and ask what makes it a fair test.
Share the objective: Comparing scientific explanations (conflicting viewpoints). Read the success criteria together.

I do: model it · 12 min

Work through the example out loud, saying why you do each step, not just what you do.
Example: Two students explain why a ball rolling on a flat floor eventually stops. Student 1: Objects naturally slow down and stop when nothing keeps pushing them. Student 2: Friction and air resistance act against the motion; with no resistive forces, the ball would keep moving at a steady speed. Which student's view agrees with Newton's first law?
Step 1: Newton's first law: an object keeps moving at constant velocity unless a resultant force acts.
Step 2: So the answer is: Student 2
Answer: Student 2
Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 min

Do these together. Students try each step on whiteboards before you reveal it.
Use the hints as prompts rather than giving the answer.

Two hypotheses explain the same data. How can scientists decide between them? (Vote on them / Ignore the data / Choose the shorter one / Design an experiment where they predict different results) → Design an experiment where they predict different resultsPrompt: Where do the two ideas disagree?
Two students explain why a ball rolling on a flat floor eventually stops. Student 1: Objects naturally slow down and stop when nothing keeps pushing them. Student 2: Friction and air resistance act against the motion; with no resistive forces, the ball would keep moving at a steady speed. Which student's view agrees with Newton's first law? (Student 2 / Neither / Both / Student 1) → Student 2Prompt: Read each viewpoint and underline its key claim.

You do: independent practice · 17 min

Students work on the student sheet. Circulate and check the first two answers of every student early.
Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

Peer review means… (other scientists check work before it is published / friends vote on the result / the scientist checks their own work only / the result can never be questioned) → other scientists check work before it is publishedPrompt: "Peers" are other experts in the same field.
Two students explain why a ball rolling on a flat floor eventually stops. Student 1: Objects naturally slow down and stop when nothing keeps pushing them. Student 2: Friction and air resistance act against the motion; with no resistive forces, the ball would keep moving at a steady speed. Which student's view agrees with Newton's first law? (Neither / Student 2 / Student 1 / Both) → Student 2Prompt: Read each viewpoint and underline its key claim.

Watch out for

Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

Review first: Evaluating experiments (research summaries).
Use concrete materials: simple equipment for a fair test.
Give the first step of each question, or a partly worked example to finish.
Pair with a confident partner for the guided practice.

Stretch

Explain a common mistake in writing and how to fix it.
Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-11.

Free lesson plan from eurekami.com/lesson-plan-builder

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Comparing scientific explanations (conflicting viewpoints)

Name

Date

Score/ 8

1
Question 1
Two students explain why a ball rolling on a flat floor eventually stops. Student 1: Objects naturally slow down and stop when nothing keeps pushing them. Student 2: Friction and air resistance act against the motion; with no resistive forces, the ball would keep moving at a steady speed. The ball rolls much further on smooth ice than on carpet. This result…
- A. supports Student 1
- B. shows friction makes things faster
- C. supports Student 2
- D. supports neither student
2
Question 2
Two scientists explain why the Moon shows phases. Scientist 1: Earth's shadow covers different amounts of the Moon during the month. Scientist 2: Half of the Moon is always lit by the Sun; as the Moon orbits Earth, we see different amounts of the lit half. Which scientist's explanation is accepted by astronomers today?
- A. Scientist 2
- B. Scientist 1
- C. both
- D. neither
3
Question 3
What makes a scientific explanation stronger than another?
- A. It explains more of the evidence and makes predictions that are confirmed
- B. It is older
- C. More people like it
- D. It is more complicated
4
Question 4
Two scientists explain why the Moon shows phases. Scientist 1: Earth's shadow covers different amounts of the Moon during the month. Scientist 2: Half of the Moon is always lit by the Sun; as the Moon orbits Earth, we see different amounts of the lit half. Earth's shadow is only on the Moon during a lunar eclipse, which happens at full moon. This evidence weakens…
- A. neither scientist
- B. Scientist 1
- C. Scientist 2
- D. both scientists
5
Question 5
Two scientists explain why some lakes have fewer fish than ten years ago. Scientist 1: Farm fertiliser washed into the lakes caused algae to grow; when the algae died, bacteria used up the oxygen in the water. Scientist 2: Warmer water from climate change holds less dissolved oxygen, so fewer fish survive. What do both scientists agree on?
- A. Fertiliser is the only cause.
- B. Low oxygen in the water harms the fish.
- C. The water is getting colder.
- D. Fish numbers have increased.
6
Question 6
A new observation contradicts a well-tested theory. What usually happens?
- A. Science stops
- B. The observation is always thrown away
- C. The theory is never changed
- D. Scientists check the observation, then improve or replace the theory if it holds up
7
Question 7
Two students explain why a ball rolling on a flat floor eventually stops. Student 1: Objects naturally slow down and stop when nothing keeps pushing them. Student 2: Friction and air resistance act against the motion; with no resistive forces, the ball would keep moving at a steady speed. Which student's view agrees with Newton's first law?
- A. Both
- B. Neither
- C. Student 1
- D. Student 2
8
Question 8
Two students explain why a metal spoon in hot soup feels hotter than a wooden spoon in the same soup. Student 1: The metal spoon is at a higher temperature than the wooden spoon. Student 2: Both spoons reach a similar temperature at the end in the soup, but metal conducts thermal energy into your hand much faster, so it feels hotter. Which student's explanation depends on how fast energy is transferred?
- A. Student 1
- B. Neither student
- C. Both students
- D. Student 2

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Answer key: Comparing scientific explanations (conflicting viewpoints)

1. C. supports Student 2
2. A. Scientist 2
3. A. It explains more of the evidence and makes predictions that are confirmed
4. B. Scientist 1
5. B. Low oxygen in the water harms the fish.
6. D. Scientists check the observation, then improve or replace the theory if it holds up
7. D. Student 2
8. D. Student 2