Photosynthesis Lab

Lesson 6 of 6: Energy Flow in Ecosystems Unit

Duration: 40 minutes
Class Size: 20 students
Grade: 7th Grade

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Learning Objectives (NGSS & Common Core Alignment)

By the end of this lesson, students will be able to:

• NGSS MS-LS1-6: Construct and interpret graphical displays of data to describe the relationship between light intensity and the rate of photosynthesis in plants.
• CCSS.ELA-LITERACY.RST.6-8.3: Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.
• CCSS.ELA-LITERACY.SL.7.5: Include multimedia components and visual displays to clarify claims and findings.
• CCSS.ELA-LITERACY.W.7.7: Conduct short research projects to answer a question (How does light affect photosynthesis?) using several sources.

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"I Can" Statements

• I can design and conduct an experiment to investigate photosynthesis.
• I can collect and record data clearly and accurately.
• I can analyze data to explain how light affects photosynthesis.
• I can communicate my findings using graphs and scientific reasoning.

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Success Criteria

• Followed experimental steps correctly and safely.
• Recorded accurate observations and measurements in a lab notebook.
• Created a graph that shows the effect of light on photosynthesis.
• Explained results using scientific vocabulary.
• Worked cooperatively and participated in group discussions.

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Materials Needed

• Elodea (aquatic plant) or spinach leaves (fresh).
• Clear water-filled test tubes or small glass containers.
• Baking soda (a source of CO2), powdered form.
• Light source (lamp with adjustable brightness or natural sunlight).
• Stopwatch or timer.
• Rulers (to measure distance of light source).
• Lab notebooks or recording sheets (dyslexia-friendly font, large print optional).
• Colored pencils or markers for graphing.
• Safety goggles.

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Lesson Breakdown

1. Introduction and Review (5 minutes)

• Briefly recap prior lessons focusing on how energy flows in ecosystems and the role of photosynthesis.
• Engage students with a quick question: "Why do plants need light?"
• Explain that today’s lab will explore how light affects photosynthesis.
• Emphasize lab safety and procedures.

Differentiation:

• Provide sentence starters or a short bilingual vocabulary list for Spanish-speaking students to participate in discussion.
• Use visuals and diagrams to reinforce concepts for students with reading challenges.

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2. Experimental Setup & Procedure Walkthrough (8 minutes)

• Model the setup: Place Elodea in water with baking soda in a test tube. Explain the role of baking soda as CO2 source.
• Show how to place the test tubes at different distances from the light source to vary light intensity.
• Explain observation goal: counting oxygen bubbles released as a measure of photosynthesis rate over time.
• Form student pairs; assign roles (timer, observer, recorder).

Differentiation:

• Provide a step-by-step visual instruction sheet with icons to support students with IEPs or dyslexia.

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3. Hands-On Lab Activity (15 minutes)

• Students conduct the experiment:
  • Place test tubes at varied distances or under different light intensities (e.g., direct lamp, shaded).
  • Count bubbles produced every 2 minutes; record data in notebooks.
  • Repeat for two trials to ensure data accuracy.

Classroom Tips:

• Circulate and assist pairs struggling with procedures or data recording.
• Partner stronger readers with students needing reading support to foster peer help.

Differentiation:

• For students with behavioral challenges, assign a steady role such as timer to keep focus.
• For gifted students: challenge them to hypothesize what would happen if CO2 levels varied.

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4. Data Analysis & Discussion (7 minutes)

• Guide students to construct simple bar or line graphs representing bubbles counted vs. distance/light intensity.
• Facilitate a group discussion:
  • What patterns do you see?
  • How does light intensity affect photosynthesis rate?
  • What might explain any variations in data?

Differentiation:

• Offer graph templates and pre-labelled graph axes for students needing extra support.
• Challenge advanced students to suggest further variables that could be tested next.

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5. Wrap-Up & Reflection (5 minutes)

• Have students complete a quick written reflection answering:
  • "What did I learn about photosynthesis and light?"
  • "What part of the experiment was easiest or hardest for me?"
• Collect reflections; review for understanding and misconceptions.

Extension Activity:

• Invite interested students to design a follow-up investigation to test different colors of light on photosynthesis.

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Assessment

• Formative: Observation of student participation and accuracy in data recording.
• Summative: Evaluate graphs and reflections using a rubric aligned with NGSS scientific practices and Common Core writing standards.
• Optional exit-ticket quiz: Multiple choice or short answer on photosynthesis and effect of light.

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Differentiation Summary

Learner Type	Strategy
English Language Learners (ELL)	Bilingual vocabulary, pictorial instructions
Students with IEPs	Step-by-step visual guides, role assignments
Gifted Students	Hypothesis challenges, designing new experiments
Behavioral Challenges	Clearly defined roles and structured tasks
Dyslexic Students	Dyslexia-friendly lab sheets, oral instructions

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Teacher Notes

• Prepare materials in advance to allow smooth transitions.
• Use visuals and gestures liberally; affirm and encourage effort especially during hands-on parts.
• Consider allowing devices for students to photograph their graphs for digital portfolios.
• Emphasize scientific vocabulary to support language acquisition and STEM literacy.

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This lesson offers a rich, student-centered lab to bring photosynthesis to life, encouraging critical thinking, collaboration, and real scientific inquiry—all aligned with Common Core and NGSS standards.