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Photosynthesis: How much light do plants actually need?


  • Project TitlePhotosynthesis: How much light do plants actually need?
  • ThemeBiology, Math, ELA
  • Submitted ByKathrine Watkevich
  • OrganizationMount Wachusett Community College
  • Brief DescriptionIn Biology, one of the main themes is how plants are able to grow, reproduce, and, more importantly, use photosynthesis to convert carbon dioxide to oxygen as they make their food. With this in mind, students were asked the question "How much light is needed for plants to grow to their fullest potential?" A simple experiment was developed where students monitored the growth of three plants. One plant grew in a normal amount of light and dark, the second was placed under constant light, and the third was placed in constant and complete darkness.
  • Materials / Resources- Prentice Hall "Biology"
    - Three Ivy plants at similar heights
    - Grow lamp
    - Tank with construction paper covering it to block out light
    - Ruler
  • Team membersMark Kuhlwein, Paul Parillo, Kate Watkevich
  • Pre-requisite knowledgeBasic math and reading skills. A general knowledge of cellular biology.

Key Questions

  • Key QuestionsIn what scenario do plants grow best (constant light/normal light/no light)?
  • Connections: How or why was this topic identified? Why is it meaningful?While covering photosynthesis and cellular respiration, students expressed interest in the role light plays in photosynthesis. Questions such as "How much light is too much?" and "Can I make a plant grow better than it would if it were to just grow on it`s own?" were brought up by students during the lesson. This led to the idea of setting up a simple experiment to test their questions. Students then spent a class developing, setting up, and running the experiment. Students took pride in this experiment because they were asking the questions and looking for an answer.
  • Background Research: What resources were used to find background information for this project?Prentice Hall "Biology"
  • Outcomes: What was the outcome? How was it shared or applied in the community?Students found that plants need both light AND dark in order to grow to their potential. Plants which received too much light did not grow as well as plants with a normal amount of light. Plants were unable to grow in the dark and died before the end of the experiment.

Units / Activities

  • Photosynthesis and Cellular Respiration 1hrUsing Prentice Hall "Biology" as a reference, students explored the role of Photosynthesis and Cellular Respiration in plant cells. The reactants and products were identified and the processes were discussed.Prentice hall "Biology"
  • Experiment development and set up 1hrStudents were given time to develop the experiment to run as well as set it up in a corner of the classroom.- 3 plants - grow light - tank - construction paper - tape - ruler
  • Measure and Graph Growth of Plants: Multiple WeeksOver the course of the experiment, students gathered quantitative observations in the form of measurements of the growth of the plants. The students completed this over the course of multiple weeks. At the conclusion of the experiment, students graphed their measurements to better visualize the results.- experiment setup
  •  /project323_4578/No Sunlight Graph.jpg/project323_4578/Normal Sunlight Graph.jpg/project323_4578/Constant Sunlight Graph.jpg
  • Practice Essay Writing Prompt 1hrAny cell`s main focus is to remain alive and reproduce to make more cells. In order to remain alive, cells must have a steady source of glucose (sugar) to use to make ATP (energy). Plant cells are unique in that they are able to make glucose with the help of carbon dioxide, water, and sunlight.
    A) What is the chemical equation for photosynthesis?
    B) What role does sunlight play in photosynthesis?
    C)In our experiment where one plant had a normal amount of sunlight, another was subjected to constant sunlight, and the third was placed in constant darkness, what were the results? How much influence does sunlight play in photosynthesis? Is it possible for a plant to receive too much light?
    D) How might we improve upon this experiment if we were to run it again?
    - Writing prompt - paper - pencil

Instructional Techniques

  • DiscussionWhile learning the content of how Photosynthesis and Cellular Respiration happen in plant cells, the students were encouraged to discuss the topic at hand and offer up any questions that they may have had. When a question was posed, other students were asked to answer and defend their answer.
  • Hands-onStudents were asked to design an experiment that would test (at the basic level) how much sunlight a plant needs in order to survive and grow. After designing the experiment, students set up the material in a corner of the classroom and continually worked (watering the plants, taking measurements, etc) until the completion of the experiment. At the end, they were asked to discuss what their conclusions were.
  • Measurement, data collection and graphingStudents measured the increase in the height of the ivy plants on a weekly basis, recorded the data, and then graphed their findings.
  • Writing prompt essay: Rough draft, peer edit, revision, final draftStudents were able to use their graphs and data collected in composing their paragraphs.

Assessment Techniques

  • WrittenBiology students were given a written quiz which contained (among other things) questions related to Photosynthesis/Cellular Respiration/The Experiment
  • DiscussionAs the experiment progressed, classes held discussions related to both qualitative and quantitative observations. Their active participation in these discussions allowed for assessment of content knowledge as well as problem solving skills as they attempted to rationalize the outcome.
  • Observation and data recordingStudents observed and measured data from the daily growth of each ivy plant. The median growth figures for each plant were recorded and translated to a bar graph point for each of the three light conditions of constant, normal and complete darkness.
  • Assess completed essays.Assessed essays as to content and knowledge of subject matter, also as to basic essay structure.

Frameworks / Skills

  • Math Frameworks (7-8)
    Create and use symbolic expressions and relate them to verbal, tabular, and graphical representations.
    (Math Frameworks (7-8))
  • Math Frameworks (7-8)
    Use tables and graphs to represent and compare linear growth patterns. In particular, compare rates of change and x- and y-intercepts of different linear patterns.
    (Math Frameworks (7-8))
  • Math Frameworks (7-8)
    Select, create, interpret, and utilize various tabular and graphical representations of data, e.g., circle graphs, Venn diagrams, scatterplots, stem-and-leaf plots, box-and-whisker plots, histograms, tables, and charts. Differentiate between continuous and discrete data and ways to represent them.
    (Math Frameworks (7-8))
  • Math Frameworks (HS)
    Select, create, and interpret an appropriate graphical representation (e.g., scatterplot, table, stem-and-leaf plots, box-and-whisker plots, circle graph, line graph, and line plot) for a set of data and use appropriate statistics (e.g., mean, median, range, and mode) to communicate information about the data. Use these notions to compare different sets of data.
    (Math Frameworks (HS))
  • ELA Frameworks (HS)
    Revise writing by attending to topic/idea development, organization, level of detail, language/style, sentence structure, grammar and usage, and mechanics.
    (ELA Frameworks (HS))
  • ELA Frameworks (HS)
    Use correct standard English mechanics such as:
    (ELA Frameworks (HS))
  • ELA Frameworks (HS)
    Use all conventions of standard English when writing and editing.
    (ELA Frameworks (HS))

Tags = biology | math | writing | Subject = ELA, Mathematics, Science | Grade Level = MS, HS | Time Period = School Year | Program/Funding = 596/597 |
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