Middle school · Science · 20 minutes
Plan a Fair Investigation
Identify a question, variables and measurements for a controlled comparison.
Middle School Science Foundations · Lesson 1 · Starter collectionLearning objective
Identify a question, variables and measurements for a controlled comparison.
Gather your materials
- Paper or a shared note-taking document
- The original passage, example or data provided in this lesson
The lesson time covers the core activity. Allow extra time for video viewing and extended discussion.
Supporting Common Core connection
SL.6.1Standard level: Grade 6
Prepare evidence, share roles, ask questions and explain how a discussion changes or strengthens your conclusion.
Read the official standard ↗This connection applies to the structured discussion below. It does not establish alignment with science or social studies content standards. Code and level checked 2026-11-04; selected skill coverage.
Teach it step by step
- Ask what the learner already knows. Introduce the objective and read the explanation together.
- Work through the example aloud. Pause for the learner to explain why each step or piece of evidence matters.
- Choose a video if useful, then connect it to the example. Let the learner complete the independent practice before checking the explained answers.
- Discuss the question below and finish with the exit check. Revisit the example if the reasoning is unclear.
Watch, notice, discuss
Video choices for this lesson
Preview a video, then choose what fits your learners. “Show to class” opens a larger view; use the player’s play and full-screen controls when you’re ready.
Teacher preview needed. Check the language, level and length before showing. YouTube may show ads or related videos.
Nature of Science
By Amoeba Sisters
Use this explanation as an introduction, then pause to connect it to the worked example and discussion question.
Open on YouTube: Nature of Science (opens a new tab) ↗Independent vs Dependent Variables
By Kyle Kobe
Compare this alternate explanation with the lesson. Ask learners to show their reasoning after watching.
Open on YouTube: Independent vs Dependent Variables (opens a new tab) ↗Which variable changes, what is measured and what stays consistent? Use the lesson’s investigation as evidence.
An external player loads only after you choose Preview or Show to class. Playback connects to YouTube. Videos belong to their creators; availability and embedding can change.
Understand the idea
A scientific investigation begins with a question that evidence can address. In a controlled experiment, the independent variable is deliberately changed and the dependent variable is measured. Other relevant conditions are kept as consistent as possible. Repeated trials help reveal variation. Conclusions describe what the evidence supports, including limits, rather than declaring that one experiment proves a universal rule.
Worked example
Question: Does water temperature affect how quickly a fixed amount of sugar dissolves? Change temperature and measure dissolving time. Keep the sugar amount, water volume, cup type and stirring procedure consistent. Use repeated trials at each temperature. If warmer water produces shorter average times in these trials, report that result for the tested conditions. An adult should prepare any warm water; avoid hot-water handling.
Try it yourself
- Identify the independent and dependent variables.
- Name three conditions that should be controlled.
- Why would one trial at each temperature be weak evidence?
Check your reasoning
- Independent: water temperature. Dependent: time for the fixed sugar amount to dissolve.
- For example, sugar amount, water volume and stirring procedure.
- A single trial may reflect random variation, timing differences or another uncontrolled condition. Repetition helps assess consistency.
Make it work for your learner
For support, model the example one step at a time and ask the learner to explain each choice in their own words. Use a sketch, organizer or physical model where helpful. For a challenge, create a new example, test an alternative explanation or describe when the model would not apply.
Exit check
Identify a question, variables and measurements for a controlled comparison. Explain your reasoning with a specific example before moving on.
Prepare · Discuss · Reflect
Use evidence in a conversation
Discussion question: Which variable changes, what is measured and what stays consistent? Use the lesson’s investigation as evidence.
- Before discussing, write a tentative answer with two details from the lesson’s passage, example or data. For a longer discussion, the teacher can add an age-appropriate source.
- In pairs, a group or a tutor–learner conversation, agree on roles: facilitator, evidence finder and note taker. Combine roles when needed and allow equal time to respond.
- Share evidence, ask a clarifying question and respond to a different interpretation. Explain which details support or challenge a claim.
- Paraphrase another person’s point. Write a final conclusion explaining what changed, what remains uncertain and what evidence you would seek next.
Teacher look-for: Accurate use of the example, reasons linked to evidence, thoughtful questions and a response to another viewpoint. A well-supported alternative answer is welcome.