Title: A Modeling Approach to Science Teaching
1A Modeling Approach to Science Teaching
Nicholas Park Greenhill School
2A 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.
3Science 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
4What 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
5Why 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.
6What 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.
7What 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
8What works
- Interactive engagement
- Student discourse articulation
- Cognitive scaffolding
- Multiple representational tools
- Consensus-based model building
- Explicit hierarchal organization of ideas and
concepts into models
9The 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
10How 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
11The Modeling Cycle
12I - 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
13II - 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.
14II - 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?
15Modeling 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
16Chemistry
17Algorithms 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?
18How 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.
19Do 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.
20Wheres 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?
21Uncovering 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
22Sample 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
23Sample 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.
26Recap 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
27For 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.