• 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.

1. Experiment 1: A pendulum with a 0.5 kg bob was timed for 10 swings with string lengths of 0.25 m, 0.50 m and 1.00 m. Experiment 2: A 1.00 m pendulum was timed with bobs of 0.1 kg, 0.5 kg and 1.0 kg. In Experiment 2, which variable was changed on purpose? (the temperature of the room / the string length / the time for 10 swings / the mass of the bob) → the mass of the bobPrompt: Look only at the description of Experiment 2.
2. 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. Which variable was kept constant in Experiment 2 but changed in Experiment 1? (the drop height / the mass of the ball / the bounce height / the floor surface) → the drop heightPrompt: What was tested in Experiment 1?
3. Hypothesis: "Plants grow faster in blue light than in red light." Which experiment tests it best? (Plants in blue light only / Identical plants under blue or red lamps of equal brightness, same water and temperature / Different species under the same lamp / One plant in blue light outdoors and one in red light indoors) → Identical plants under blue or red lamps of equal brightness, same water and temperaturePrompt: Only the colour of light should differ.

• 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.

• 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.

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

1. What makes a scientific explanation stronger than another? (It is older / It explains more of the evidence and makes predictions that are confirmed / More people like it / It is more complicated) → It explains more of the evidence and makes predictions that are confirmedPrompt: Scientists judge ideas by evidence.
2. 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? (Both students / Student 1 / Neither student / Student 2) → Student 2Prompt: Read each viewpoint and underline its key claim.

• 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.

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

1. 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 / Student 1 / Both students) → Student 2Prompt: Read each viewpoint and underline its key claim.
2. Two hypotheses explain the same data. How can scientists decide between them? (Ignore the data / Choose the shorter one / Vote on them / Design an experiment where they predict different results) → Design an experiment where they predict different resultsPrompt: Where do the two ideas disagree?

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