Conceptual Representations for Learning about Complex Biological Systems: From Expertise to Instruction

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Conceptual Representations for Learning about
Complex Biological SystemsFrom Expertise to
Instruction

• Cindy E. Hmelo-SilverRutgers Universitycindy.hme
  lo-silver_at_gse.rutgers.edu

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Overview

• Understanding complex systems
• Structure-Behavior-Function (SBF) as a conceptual
  representation
• Expert-novice differences in complex systems
  understanding
• Conceptual Representations embodied in
  instruction
• Hypermedia
• NetLogo
• Into the classroom

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Why Learn about Complex Systems?

• Ubiquitous in the world
• Human systems
• Cities
• Ecosystems
• Important for understanding many aspects of
  science
• Potential to integrate across disciplines

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Understanding Complex Systems

• Difficult because
• Multiple levels of organization that often depend
  on local interactions (Wilensky Resnick, 1999)
• Invisible, dynamic phenomena pose barriers to
  understanding
• Conflict with learners prior experience
  (Feltovich et al., 2001)
• Indirect causality (Perkins Grotzer, 2000)

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Novice Understanding

• Focus on the perceptually available structures
  (Hmelo, Holton, Kolodner, 2000 Wood-Robinson,
  1995 Hmelo-Silver Pfeffer, 2004)
• Favor simple explanations, central control
  (Jacobson, 2001)
• But can conceptual representations provide
  organizing frameworks for learning about such
  systems?
• Examples Emergence, Structure-behavior-function

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Structure-Behavior-Function (SBF) theory

• Allows effective reasoning about the functional
  and causal roles played by structural elements in
  a system (Goel et al., 1996).
• Structures refer to elements of a system
• Fish
• Filter
• Behaviors refer to how the structures of a system
  achieve their purpose or output
• Filters remove waste by trapping large particles,
  absorbing chemicals, and converting ammonia into
  harmless chemicals
• Why Functions refer to why an element exists
  within a given (designed) system or the output of
  the system
• The filter removes byproducts from the aquarium

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Studying SBF as a conceptual representation

• Expert-novice study
• Two domains
• Aquariums
• Human respiratory system

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Participants

• Respiratory System Interview
• 21 Middle school students
• 20 Pre-service teachers
• 13 Experts (8 respiratory therapists, 5 pulmonary
  physicians)

• Aquarium Interview
• 20 Middle School Students
• 26 Preservice Teachers
• 9 Experts (5 hobbyists, 4 biologists)

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Coding and Analysis

• Interviews were coded according to SBF coding
  scheme for the presence or absence of a target
  concept.
• Structure
• There is sand on the bottom
• The trachea is divided into two parts
• Behavior
• Fish hide between the plants
• The brain sends a signal for the diaphragm to
  contract downward
• Function
• A filter filters out organic waste
• Lungs bring air into your body

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Results Respiratory System
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Sample Responses What do the lungs do?

• Expert The lungs, pretty much are the place of
  oxygen gas exchange. Its where oxygen comes into
  the body. Its where acid load by carbon dioxide
  is released from the body. Thats its primary
  function.The tissue lungswell you
  haveACE-inhibitor break downyou haveyou also
  have I think insulin break down. Also that occurs
  in the lungs too. You have oxygen exchange.
  Thats primary purposelungs are oxygen exchange,
  well oxygen gas exchange. Im sorry let me get
  that correct, gas exchange because you dont want
  to leave the carbon dioxide out, which is just as
  important, and its also a mechanism for managing
  acidosis, pH balance, because its one of the most
  quick, its the most rapid management. You can
  blow off CO2 even if the CO2 is normal to
  maintain a decent pH, so its one of the quick
  modes of balance, pH balance.
• Pre Service Teacher The lungs transfer air,
  transfer oxygen and carbon dioxide I believe back
  and forth from the blood stream and the air sacs
  within the lungs in order to provide it to the
  blood system.
• Middle School Student Well, they ah, its where
  the air goes like it helps you breathe. I dont
  want to say pumping, but it um, something like
  that.

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Results Aquarium Systems
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Sample responses What do fish do in an aquarium?

• Expert Hmm. Um, in an aquarium, fish will do
  many of the same things that they do in their
  natural life. Theyll forage for food, they will
  uh, seek mates and attempt to mate. And many
  times they will successfully reproduce. Um, they
  eat, they sleep, they burrow for shelter, and
  they go through a lot of social aggression,
  interactions, dominance. They establish dominance
  and attempt to maintain it over other fishes in
  the tank. Or uh, go in a submissive mode and
  spend a lot of time hiding from dominant fishes
  in the tank. Specifically, you could list a
  whole bunch of physiological uh, levels of things
  that fishes do. Like respire, digest, uh grow, um
  die.
• Pre service teacher They swim aroundtheythats
  where they liveso thats like where their whole
  habitat is, thats where there whole life is
  
• Middle School Student They swim around, cause
  its like, their like, mini-natural habitat. Fish
  always swim in water, so its like a converse
  size of their habitat.

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Qualitative Analyses

• Expert interviews
• Provided more elaborate responses
• Demonstrated a more integrated understanding that
  cut across the SBF levels.
• Novice interviews
• Mentioned numerous structures

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Expert-Expert Analyses

• All have rich understanding, ? emphases
• Biologists/ Pulmonologists tended to have more
  global, abstract understanding
• Hobbyists/ Respiratory Therapists more local,
  situated understanding

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Biologist Model of Filter

• Focused on properties of filter as substrate for
  bacterial growth
• Relationship bet pH and filtration
• No discussion of nitty-gritty of behavior
• Somewhat abstract

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Hobbyist Model of Filter

• Talk about multiple functions of filter
• Composition and mechanics
• ? kinds of materials and their purposes
• Connects to other elements of system

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Pulmonary Physician Modelof Respiratory System

• Looks at system from many levels
• CNS and control
• Feedback loops
• External Respiration
• Internal Respiration

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Respiratory Therapist Mental Model

• Discuss multiple levels but lungs are central
• Focus on functions and behavior that have direct
  implication for practice

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Discussion

• Visible structures are best understood.
• For the experts, behavioral and functional levels
  are deep principles that organize their knowledge
  of the system.
• Although all experts have deep knowledge, there
  are interesting differences
• Biologists/ Physicians think in global and
  abstract ways.
• Hobbyists/ Respiratory therapists think in local
  and situated ways.
• Raises issue of what are appropriate target
  models for instruction

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Implications

• The SBF framework may function as a deep
  principle that maps on to
• expert ways of understanding complex systems
• structure of domain.
• SBF framework offers a way for learners to look
  behind the scenes at phenomena that are not
  readily perceptually available.
• Organizing learning around deep principles such
  as SBF might enable students to understand new
  complex systems they encounter

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Conceptual Representations in Hypermedia

• Organizing text and graphics based on
• Expert understanding
• Deep principles of domain
• SBF as conceptual representation
• Proof of concept for emphasizing function

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Function-centered Hypermedia
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Structure-Centered Hypermedia
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Comparing Function-centered vs.
Structure-centered hypermedia

• Participants 52 undergraduates enrolled in
  Educational Psychology
• Random assignment to structure- or function-
  centered condition respiratory system hypermedia
• Procedure
• Students worked with hypermedia x 40 min
• Written post-test on respiratory system
  understanding
• Scoring
• SBF coding scheme for the target concepts.
• Structure
• The trachea is divided into two parts
• Behavior
• The brain sends a signal for the diaphragm to
  contract downward
• Function
• Lungs bring air into your body

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Results Visible SBF

• Visible SBF includes macrolevel phenomena
  involved with external respiration
• Organ level such as airways, brain, diaphragm,
  heart, lungs, muscles, ribs
• No significant differences across conditions

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Invisible SBF

• Includes microlevel structures and phenomena
  related to gas exchange, transport, and internal
  respiration
• e.g. alveoli, blood, capillaries, cellular
  respiration, red blood cells
• Rarely mentioned by novices in baseline study

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RepTools Aquarium Tools
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Function-centered Aquarium Hypermedia System
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Simulations and Modeling

• Allow learners to experience complex systems
  phenomena
• Simulations and models help focus learners on
  function and behavior
• Make invisible phenomena visible and open for
  inspection
• NetLogo as platform for model development
  (Wilensky, 1999)
• Agent-based modeling tool
• High-threshold, low ceiling
• Allow understanding of how local interactions
  contribute to system behavior

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NetLogo Aquarium Model
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Nitrification model
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In the Classroom

• Providing scaffolding and sequencing that help
  establish why questions
• Mix of hands-on activities, hypermedia resources,
  simulations, class discussions
• Scaffolding needs to encourage mapping
• Between real world and virtual world
• Between different levels
• Considering how models simplify the world

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Research Context

• Goal to support middle school science instruction
  in domain of aquarium ecosystem
• Units developed with two collaborating teachers
• 145 middle school students in 2 public schools
  for about 2 weeks
• 70 7th grade with Teacher A
• 75 8th grade with Teacher B
• Both classrooms had physical aquaria and 1-2
  laptops for each small group

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Teaching Contexts

• Both teachers experienced, considered experts
• Teacher A
• Used worksheets with open-ended questions
• Expected homogeneous progress for whole class
• Focus on content
• Teacher B
• Inquiry-oriented norms for classroom
• Scaffolded exploration by asking students to
  observe and explain, open-ended questioning

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Research Design

• Pre and post tests of SBF knowledge (Hmelo et al,
  2007)
• Comparisons among classroom
• Qualitative analysis of enactments using
  Interaction Analysis (Jordan Henderson, 1995)

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Learning Outcomes
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Enactments

• Although both teachers showed significant gains,
  IA showed great differences in enactment
• Two areas
• Creating opportunities for inquiry
• Interpretation of computer models

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Creating Opportunities for InquiryTeacher A
Adoption of Student Language

• Concentration on definitions of terms
• Posed questions requiring one-word response to
  class as whole
• Questions aimed at reproducing declarative
  knowledge
• Adoption of student language to convey behavior
  of structures
• Results suggest student understanding was
  scaffolded by connecting to prior knowledge as a
  way to explain new concepts

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Adopting Student Language

• Teacher A First of all you understand that
  certain things are living and certain things
  arent. Right? Is ammonia a living creature?
• Class No!
• Teacher A It doesnt grow, it doesnt reproduce,
  it doesnt respond. How do I get more ammonia in
  the tank?
• Class Pee
• Teacher A Pee. Its not like its reproducing
  and making more. You want more. You want more,
  you get more fish and more fish do what?
• Class Pee!

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Creating Opportunities for InquiryTeacher B
Scientific Terminology and Inquiry Orientation

• Open-ended questions requiring explanations
• Promoted argumentation in student discourse
• Incorporation of new scientific terminology

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Scientific Terminology and Process Inquiry

• Alexis What would happen if there were no
  fish?
• Courtney Well first of all, uh, snails wouldnt
  have anything to eat.
• Ron Were not talking about snails.
• Alexis Were talking about fish.
• Courtney But they need to have they wouldnt
  make the water dirty. So then the fish wouldnt
  have
• Ron Alright, so they wouldnt produce waste.
  Were not talking about the snails.
• Alexis I just think that there would be no
  point. What are we going to have a plant farm in
  water?
• Courtney Basically, nothing would be able to
  work because the bacteria
• Jenn Everything lives on fish.
• Courtney The fish produce ammonia, which
  bacteria makes less harmful and snails keep the
  water clean by cleaning the waste and the algae.
• Ron OK, so fish are the basis of all this
  ecosystem.

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Interpretation of Computer ModelsTeacher A
Technology for Instruction

• NetLogo as a teaching aid
• Reinforce content knowledge
• Concern with student understanding of computer
  model as end in itself
• Homogeneous understanding

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Technology Use to Provide Instruction

• Teacher A Lets go over the key. Did you figure
  out what this is?
• Class Yeah.
• Teacher A What is it?
• Class Plants.
• Teacher A Brilliant, thats a plant, you got
  that one. Writes it on board Did you get the
  red dots?
• Class Yeah.
• Teacher A Whats that?
• Class Ammonia.
• Teacher A Very good. OK now Im going to make it
  a little harder. White dots?
• Class Nitrite.
• Teacher A Because what appeared first?
• Class Ammonia.
• Teacher A Red dots. And what appeared second?
• Class White dots.

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Interpretation of Computer ModelsTeacher B
Technology as a Cognitive Tool

• Technology as cognitive tool
• Affords inquiry
• Science as a model building activity
• Groups notice different aspects of model
• Stimulate cognitive engagement
• Use of RepTools to foster deep understanding
• Promotion of scientific inquiry
• Co-construction of knowledge among group members

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Technology as a Cognitive Tool

• Teacher B how are you going to know whether
  the blue boxes are snails, bacteria, whats the
  other stuff you said, algae, stuff like that?
• Courtney I dont think its bacteria because the
  red is ammonia and its not eating, its not
  getting rid of it.
• Teacher B How do you know that?
• Courtney Because, um well, you can see the
  ammonia on top of it and its not doing anything
  to it.
• Teacher B Well its paused right now.
• Courtney Well also because the ammonia is
  increasing and while these things are increasing
  too its not decreasing the amount of ammonia.
• Teacher B Its not?
• Courtney No, well thats what I observed. Am I
  wrong?
• Teacher B No, no.
• Ron Say that again, Courtney
• Courtney I said, I think that the blue cant be
  bacteria because bacteria eats ammonia and while
  the blue is increasing the ammonia is still
  increasing too so if the blue was bacteria

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Discussion

• A tale of two classrooms
• Different cultures
• Different beliefs about learning and inquiry
• Appropriation of tools consistent with beliefs
• Both teachers
• Considered expert
• Willing to take risks
• Despite differences, similar outcomes
• Additional analysis to understand differences

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Future Directions

• Need to better understand learning processes
• Fine grained analysis of discourse (Liu, 2008)
• Effects of teacher guidance (Marathe, in
  progress)
• More explicit guidance in SBF thinking
• ACT (Aquarium Construction Tool) with colleagues
  at Georgia Institute of Technology

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For More Information

• cindy.hmelo-silver_at_gse.rutgers.edu

RepTools software available at
reptools.rutgers.edu
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Challenges for Supporting Learning about Complex
Systems

• Cognitive Challenges
• Prior knowledge
• Developmental level
• Reasoning Strategies
• Inquiry skills
• Metacognitive Challenges
• Planning, monitoring, and evaluating ones
  understanding
• Self-regulatory and motivational strategies may
  be lacking (Azevedo et a., 2005)
• Need for open-ended learning environments WITH
  scaffolding to help learners deal with complexity