Grade Range
6th-8th
Group Size
3 students
Active Time
Part 1: 1 h 40 minutes, Part 2: 1 hour 45 minutes
Total Time
Part 1: 1 h 40 minutes, Part 2: 1 hour 45 minutes
Area of Science
Plant Biology
Key Concepts
Photosynthesis
Learning Objectives
  • Explain what happens during photosynthesis.
  • Design and conduct an experiment to investigate variables that might affect the rate of photosynthesis.
  • Graph and analyze experimental results to interpret and compare photosynthesis rates.
Credits
Svenja Lohner, PhD, Science Buddies
Cup filled with a solution and leaf disks on the bottom. One leaf disk is floating to the surface.

Overview

Plants carry out photosynthesis to produce sugars that they need as an energy source to live and grow. During photosynthesis, oxygen—a gas that many living beings need to survive—is released. This makes photosynthesis one of the most important biological processes on Earth. In Part 1 of this lesson plan, students will utilize the floating leaf disk assay to demonstrate the production of oxygen gas during photosynthesis. They will then continue to design and conduct their own experiments in Part 2 of the lesson in order to investigate variables that affect the rate of photosynthesis in plants.

Remote learning adaptation: This lesson plan can be conducted remotely. The Engage section of the lesson can be skipped or done over a video call, then students can work independently during the Explore sections, using the Student Worksheet and the Leaf Disk Assay Video as a guide. Students will need to obtain their own materials such as a light source and a plastic syringe. For Part 2 of the lesson, students can adjust the independent variable they will investigate according to the materials available to them. The data analysis in the Reflect sections and the presentations of the results can be done over a video call, or by sharing a poster or slides on a class drive.

NGSS Alignment

This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:
  • MS-LS1-6. Construct a scientific explanation based on evidence for the role of photosynthesis in the cycling of matter and flow of energy into and out of organisms.
This lesson focuses on these aspects of NGSS Three Dimensional Learning:

Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Planning and Carrying Out Investigations. Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.

Conduct an investigation and/or evaluate and/or revise the experimental design to produce data to serve as the basis for evidence that meet the goals of the investigation.

Collect data about the performance of a proposed object, tool, process, or system under a range of conditions.

Analyzing and Interpreting Data. Analyze and interpret data to determine similarities and differences in findings

Engaging in Argument from Evidence. Construct, use, and/or present an oral and written argument supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.
LS1.C: Organization for Matter and Energy Flow in Organisms. Plants, algae (including phytoplankton), and many microorganisms use the energy from light to make sugars (food) from carbon dioxide from the atmosphere and water through the process of photosynthesis, which also releases oxygen. These sugars can be used immediately or stored for growth or later use.
Energy and Matter. Within a natural system, the transfer of energy drives the motion and/or cycling of matter.

Materials


Materials needed for the 'Study Photosynthesis with the Floating Leaf Disk Assay' lesson.

For each student group of 3:

  • Green plant leaves, such as spinach or ivy
  • Single hole puncher or sturdy straw
  • Transparent cups, 5 or more (large enough to hold 300 mL)
  • Baking soda (1/8 teaspoon)
  • Tap water (room temperature)
  • 1/4 or 1/8 teaspoon
  • Measuring cup
  • Liquid dish soap
  • Plastic syringe, 10 mL or bigger (without the needle)
  • Light source. Note: Any lamp with a CFL, halogen, incandescent, fluorescent, or LED bulb should work. The brighter the light, the better. With incandescent lightbulbs you have to be careful not to generate too much heat! You can also use direct sunlight outside. The type of light source will affect the rate at which photosynthesis happens. This is one variable that can be tested by students.
  • Aluminum foil
  • Permanent marker
  • Paper towels
  • Timer
  • Lab notebook
  • Pencil or pen
  • Calculator
  • Paper

For teacher:

  • Bowl
  • Aluminum foil

Extra materials for independent student investigations:

  • To investigate the following:
    • Different light sources: LED, CFL, incandescent, halogen, sunlight
    • Different light intensities: Ruler or measuring tape
    • Different light colors: Colored cellophane sheets, tape
    • Water temperature: Thermometer, microwave, ice cubes
    • Different leaf colors: Yellow, red, and green leaves
    • Different plant types: Leaves from different plant species

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Grade Range
6th-8th
Group Size
3 students
Active Time
Part 1: 1 h 40 minutes, Part 2: 1 hour 45 minutes
Total Time
Part 1: 1 h 40 minutes, Part 2: 1 hour 45 minutes
Area of Science
Plant Biology
Key Concepts
Photosynthesis
Credits
Svenja Lohner, PhD, Science Buddies
Learning Objectives
  • Explain what happens during photosynthesis.
  • Design and conduct an experiment to investigate variables that might affect the rate of photosynthesis.
  • Graph and analyze experimental results to interpret and compare photosynthesis rates.
Free science fair projects.