Why Don't We Always Perceive Correctly?

Lance Pearson

Number of Learners: 90 Students

Date: 05/14/05

Grade (or Age): 8th grade

School/Town: Timilty Middle/Roxbury

Estimated Length of Session: 40-50 minutes

Curriculum Area: Science (Biology)

PREREQUISITE KNOWLEDGE AND SKILLS

None is necessary.

CONTENT TO BE TAUGHT

This lesson plan is aimed at undeniably demonstrating that there can be a difference between our visual perception (our mind's eye view) of the world and reality itself.  It is also aimed at motivating an interest in scientific explanations for why these problems result and what the brain has do do with it.

RATIONALE

Unlike the growth of producers or consumers which are invariably integral parts of the science curriculum, students in urban school settings are rarely asked to deeply examine the processes of decay and decomposition. This guided-inquiry lesson plan rounds out the standard life cycle curriculum with in-depth scientific observations of the mechanisms of decomposition and decay. In so doing, it fulfills one of the more neglected Massachusetts Frameworks Life Science (Biology), Grades 6–8 curriculum standards: 15. Explain how dead plants and animals are broken down by other living organisms and how this process contributes to the system as a whole.

An additional rationale for implementing this curriculum is that it fits seamlessly as a supplement to the existing FOSS Populations & Ecosystems curriculum, paralleling the existing terrarium project in both timing and design. As such, it can be added with a minimum of additional class and teaching time.

GOALS

  • Students will collaborate amongst themselves (jigsaw) to explore some of the principle decomposers in the urban environment.
  • Students will design an experiment to monitor the decomposition of a plant and an animal.
  • Students will engage in self-generated data observation to (a) hone their scientific writing and observational skills and (b) form conclusions about the processes of decomposition.
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    PERFORMANCE OBJECTIVES

  • Students will observe some of the principal decomposers in an urban environment by designing an experiment to record decay over the course of weeks of a plant and an animal under differing conditions.
  • Each student will be responsible for proposing an experimental protocol related to the way in which plants and animals decompose including: a) an experimental question, b) an experimental hypothesis, c) a list of materials, d) an experimental design consisting of at least 5 different steps, and e) a sample data sheet.
  • Each student will be required to design a data sheet and make detailed and regular observations (during the first 5 minutes of every class for two weeks) of the class' science experiment. Students will be monitored and graded upon relevance, detail and accuracy of their selected data.
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    MATERIALS

  • Computer with MS Powerpoint capability
  • LCD projector for the presentation
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    Alternatively
  •  The still pictures can be printed out on transparencies and shown on an overhead
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    PROCEDURE

    This curriculum works best

    A. Opener
  • Answer the questions on the handout as we move through the slideshow
  • Emphasize that there are no right or wrong answers during this portion of the class, what other people write down is not important. Instruct them to simply answer what the pictures look like to them.
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    B. Development
  • Student discuss their answers about their perception of these phenomena and propose ways to verify their answers (e.g. use meter stick to check for linearity).
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  • Students are prompted to explore the implications these demonstrations have for the confidence they should have in their senses.
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    C. Closing
  • How could we double-check (verify) whether what you (or anyone else) are seeing is what is actually there?
  • Summarize the central conclusion that should now be clear to the students: there can be a difference between our perceptions and reality.  Also emphasize that we can become aware of these differences (errors) (a) when other people have different perceptions than ours, (b) when our other senses provide contradictory information or when (c) our perceptions of other objects provide inconsistent comparisons.
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    ACCOMMODATIONS

    Establishing a word wall with key words and definitions like Perception and Reality together with their definitions can be a great assistance to English-learners.

    EVALUATION

    The accompanying worksheets provide a baseline measure of attentiveness and participation.  If desired an additional worksheet can be quickly drawn up requiring students to write down possible ways to test the validity of their perceptions of each of the illusions as we move through them.  Student involvement in discussion of the phenomena can also be used for assessment as well.

    EXTENSION

    Additional lesson plans in the series present various examples of visual, auditory and tactile illusions.  Students may explore other visual illusions online or research scientific explanations for particular illusions they find interesting.  The entire unit has numerous natural tie-ins with other subject areas, particularly writing and social studies (civics). 

    REFERENCES

    Hermann Grid

    Hering Illusion

    Cafe Wall Illusion

    Checker-Shadow Illusion

    Neon Color Spreading

    Retinex Color

    ASSOCIATED APPENDICES

    Appendices for "Why Don't We Always Perceive Correctly?" Lesson Plan