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A Modeling Approach to Science Teaching

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We go through life collecting memories, and organizing them into mental models, ... An inconsistently applied, private model based on miscellaneous experiences. ... – PowerPoint PPT presentation

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Title: A Modeling Approach to Science Teaching


1
A Modeling Approach to Science Teaching
Nicholas Park Greenhill School
2
A Private Universe
  • We go through life collecting memories, and
    organizing them into mental models, or schema.
  • Our memory depends on connections new inputs
    which do not fit in an existing schema tend to be
    forgotten.
  • It takes a very discrepant phenomenon to motivate
    a change in existing schemata.

3
Science and Modeling
  • Scientists construct and use shared models to
    describe, explain, predict and control physical
    sytems.
  • By making this process explicit, we help students
    to
  • Revise their mental schemata (models) in the
    light of experimental evidence and collaborative
    discourse
  • Understand the scientific process

4
What Do We Mean by Model?
  • Essential and non-essential elements of a
    physical system or process are identified
  • Models are used to represent the structure
    underlying the essential elements

5
Why Models?
  • Models are basic units of knowledge
  • A few basic models are used again and again with
    only minor modifications.
  • Students DO work from mental models the
    question is which model it will be
  • A shared, rigorous model with explicit
    experimental support?
  • An inconsistently applied, private model based on
    miscellaneous experiences.

6
What about problem solving?
  • The problem with problem-solving
  • Students come to see problems and their answers
    as the units of knowledge.
  • Students fail to see common elements in novel
    problems.
  • But we never did a problem like this!
  • Models as basic units of knowledge
  • A few basic models are used again and again with
    only minor modifications.
  • Students identify or create a model and make
    inferences from the model to produce a solution.

7
What doesnt work
  • Presentation of facts and skills, with the
    assumption that students will see the underlying
    structure in the content.
  • They systematically miss the point of what we
    tell them.
  • They do not have the same schema associated
    with key ideas/words that we have.
  • Students passively listen while T works

8
What works
  • Interactive engagement
  • Student discourse articulation
  • Cognitive scaffolding
  • Multiple representational tools
  • Consensus-based model building
  • Explicit hierarchal organization of ideas and
    concepts into models

9

The Modeling Method
  • Construct and use scientific models to describe,
    to explain, to predict and to control physical
    phenomena.
  • Model physical objects and processes using
    diagrammatic, graphical and algebraic
    representations.
  • Recognize a small set of models as the content
    core.
  • Evaluate scientific models through comparison
    with empirical data.
  • View modeling as the procedural core of
    scientific knowledge

10
How to Teach it?
constructivist vs
transmissionist cooperative inquiry vs
lecture/demonstration student-centered vs
teacher-centered active engagement vs
passive reception student activity
vs teacher demonstration student articulation
vs teacher presentation
lab-based vs textbook-based
11
The Modeling Cycle
12
I - Model Development
  • Students in cooperative groups
  • design and perform experiments.
  • formulate functional relationship between
    variables.
  • evaluate fit to data.
  • Post-lab analysis
  • whiteboard presentation of student findings
  • multiple representations
  • justification of conclusions

13
II - Model Deployment
  • In post-lab discussion, the instructor
  • brings closure to the experiment.
  • fleshes out details of the model, relating common
    features of various representations.
  • helps students to abstract the model from the
    context in which it was developed.

14
II - Model Deployment
  • In deployment activities, students
  • learn to apply model to variety of related
    situations.
  • identify system composition
  • accurately represent its structure
  • articulate their understanding in oral
    presentations.
  • are guided by instructor's questions
  • Why did you do that?
  • How do you know that?

15
Modeling in a Nutshell
  • Through carefully guided discourse, students
    construct shared models, using various
    representations, to describe shared experiences
    with physical systems and processes.
  • Let the students do the talking
  • Ask, How do you know that?
  • Require diagrams and representations whenever
    possible

16
Chemistry
  • A Closer Look

17
Algorithms vs Understanding
  • What does it mean when students can solve
    stoichiometry problems, but cannot answer the
    following?

Nitrogen gas and hydrogen gas react to form
ammonia gas by the reaction N2 3 H2 ? 2
NH3The box at right shows a mixture of nitrogen
and hydrogen molecules before the reaction
begins. Which of the boxes below correctly shows
what the reaction mixture would look like after
the reaction was complete?
18
How Do You Know?
  • All students know the formula for water is H2O.
  • Very few are able to cite any evidence for why we
    believe this to be the case.

19
Do They Really Have an Atomic View of Matter?
  • Before we investigate the inner workings of the
    atom, lets make sure they really believe in
    atoms.
  • Students can state the Law of Conservation of
    Mass, but they will claim that mass is lost in
    some reactions.
  • When asked to represent matter at sub-microscopic
    level, many sketch matter using a continuous
    model.

20
Wheres the Evidence?
  • Why teach a model of the inner workings of the
    atom without examining any of the evidence?
  • Students know the atom has a nucleus surrounded
    by electrons, but cannot use this model to
    account for electrical interactions.
  • Why disconnect the Bohr model of the atom from
    the effort to understand the hydrogen line
    spectrum?

21
Uncovering Chemistry
  • Examine matter from outside-in instead of from
    inside-out
  • Observable Phenomena ? Model
  • Students learn to trust scientific thinking, not
    just teacher/textbook authority
  • Organize content around a meaningful Story of
    Matter

22
Sample Cycle Density
  • Prerequisite activities
  • Define volume by counting cubes, and validate
    the formulas learned in math.
  • Define mass as amount of matter, measured using a
    balance.
  • Develop law of conservation of mass through a
    lab with physical and chemical changes

23
Sample Cycle Density
  • Density Lab and Follow-up
  • Question What is the relationship between the
    mass of a solid and its volume?

24
  • Even if students correctly say mass per unit
    volume rather than mass per volume in
    interpreting M/V, there is no conclusive
    assurance that they really understand the
    meaning. Some do, but others have merely
    memorized the locution. It is important to lead
    all students into giving simple interpretation in
    everyday language before accepting a regular use
    of per. Many students do not know what the
    word ratio means. Those having difficulty with
    reasoning and interpretation should always be
    asked, at an early stage, for the meaning of the
    word if they, the text, or the teacher invoke
    it.
  • A Arons, Teaching Introductory Physics, John
    Wiley Sons, 1997.

25
  • In worksheet 3 students make comparisons of the
    mass, volume and density of pairs of objects
    based on particle representations.
  • Worksheet 4 further reinforces the notion that
    the slope of a graph has physical meaning.
  • The first quiz requires students to determine the
    slope and perform standard calculations involving
    density.
  • In next activity Density of a gas, students
    determine the density of carbon dioxide. The
    fact that the value is 3 orders of magnitude
    smaller than that of liquids and solids sets the
    stage for the discussion of an atomic model of
    matter that accounts for this difference.

26
Recap What works
  • Interactive engagement
  • Student discourse articulation
  • Cognitive scaffolding
  • Multiple representational tools
  • Consensus-based model building
  • Explicit hierarchal organization of ideas and
    concepts into models

27
For more information
  • Local workshops next summer (hopefully!) in
    physics, chemistry, and physical science.
  • Modeling curricula do an excellent job sequencing
    the curriculum to provide a good storyline and to
    facilitate model construction and deployment.
  • Elements of the modeling approach can be adapted
    to any curriculum.
  • I am happy to provide advice, resources, or
    assistance.
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