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: A student dropped the same ball from heights of 0.5 m, 1.0 m and 1.5 m onto a wooden floor and measured the bounce height. Experiment 2: The student dropped the same ball from 1.0 m onto wood, carpet and concrete. In Experiment 2, which variable was changed on purpose? (the mass of the ball / the drop height / the floor surface / the bounce height) → the floor surfacePrompt: 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 number of seeds that germinated / the temperature / the colour of the pots / the volume of water) → 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 stop expectations from biasing the results / To make the trial shorter / Because the drug is secret / To save money) → 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.

What makes a scientific explanation stronger than another? (More people like it / It is more complicated / It is older / It explains more of the evidence and makes predictions that are confirmed) → It explains more of the evidence and makes predictions that are confirmedPrompt: Scientists judge ideas by evidence.
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? (Neither student / Student 2 / Both students / 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.

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 1 / Neither / Both / Student 2) → Student 2Prompt: Read each viewpoint and underline its key claim.
Two hypotheses explain the same data. How can scientists decide between them? (Design an experiment where they predict different results / Vote on them / Ignore the data / Choose the shorter one) → Design an experiment where they predict different resultsPrompt: Where do the two ideas disagree?

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 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. The water is getting colder.
- B. Low oxygen in the water harms the fish.
- C. Fish numbers have increased.
- D. Fertiliser is the only cause.
2
Question 2
What makes a scientific explanation stronger than another?
- A. It explains more of the evidence and makes predictions that are confirmed
- B. It is more complicated
- C. More people like it
- D. It is older
3
Question 3
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 neither student
- D. supports Student 2
4
Question 4
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 2
- B. Both students
- C. Student 1
- D. Neither student
5
Question 5
Peer review means…
- A. friends vote on the result
- B. the result can never be questioned
- C. the scientist checks their own work only
- D. other scientists check work before it is published
6
Question 6
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. A lake far from any farm also lost fish as it warmed. This supports…
- A. neither scientist
- B. Scientist 2
- C. Scientist 1
- D. only that fertiliser is harmless
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. Student 1
- B. Student 2
- C. Neither
- D. Both
8
Question 8
A new observation contradicts a well-tested theory. What usually happens?
- A. Scientists check the observation, then improve or replace the theory if it holds up
- B. The observation is always thrown away
- C. The theory is never changed
- D. Science stops

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Answer key: Comparing scientific explanations (conflicting viewpoints)

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