VMODEL

Kenneth D. Forbus

Karen Carney

Robert T. Harris

Bruce Sherin

Northwestern University

Overview

• Why should students model?• Our approach• Design and architecture of Vmodel

– Key design tradeoffs

– Ontological assumptions

– Three perspectives: • Situation map, causal map, evidence map

– Model Library

– Plans for coaching

• Curriculum development• Future Work & Next Steps

Why should students model?

• Models provide externalization of thought– Reduce working memory load– Facilitate communication with others

• Modeling valuable skill for students– Central skill in scientific reasoning– Forces students to articulate relationships– Supports understanding of complex systems

• Important goal in AAAS standards

• Provides practice in using formal representations– Learning “the rules” important for mathematics,

programming– Qualitative modeling formalisms provide a more

approachable experience

Helping middle school students see the underlying unity of science

WarmthDensity

Heat inCoffee

WarmthDensity

Heat inLower Atmosphere

Cool, Dense AirIn upper AtmosphereCool, Dense Cream

WarmthDensity

Hmmm. The movement of air in the atmosphere has elements in common with cream churning in coffee.

Reification to facilitate transfer

• Modeling environment should – Support creating new abstractions

– Support specifying when they are relevant

– Support reuse (aka transfer) of these principles

WarmthDensity

Heat inFluid Medium

Cool, Dense Substance What makesTectonic Plates Move?

I’ll call this thingConvection.

Convection!

How do we get students to model?

• One solution: Visual representations

• Three families have been used

1. Concept maps– Describe structural, functional properties and relationships.

– Have been used by elementary school students

2. Dynamical systems notations– Examples: Forrester’s System Dynamics (STELLA, Model-It),

Bond Graphs

– Can handle ODE’s in a single process structure, produce graphs via numerical simulation

3. Argumentation environments– Examples: Belvedere, KIE, Collaboratory Notebook

– Provides medium for students to marshal evidence, construct arguments for and against hypotheses

Limitations

• Concept maps– Lack of standardized, formal meaning

• Paths read as if natural language sentences

• Often difficult for students to understand each other’s maps

• More difficult for software to understand student maps

• Dynamical systems notations– Don’t express conditions under which model is

appropriate

– Requiring numerical models, data often overkill

• Argumentation environments– Work at large grain size (web page or paragraph)

• Hard to understand/scaffold student work

All current systems ignore three key issues in modeling

1. Importance of broadly applicable principles and processes– Existing systems don’t help students construct a systematic body

of knowledge• Ex: Convection, heat flow, other processes widely used in scientific

explanations

2. Understanding when a model is relevant– Articulating and using modeling assumptions

• Ex: plant life infinite fine for continental predator/prey model, not for island or space station.

3. Qualitative understanding of behavior– Mathematics distracts students from understanding behavior

• Formulating influences easier than formulating complete equations.

– Shifts minimum age upwards for modeling activities

Our Approach

• Create new visual modeling language and tool– Combine best aspects of previous three families

– Organize as multiple perspective, highly constrained concept map language

• Use qualitative process theory and compositional modeling to provide strong semantics

• Provide Model Library as scaffold for abstraction– Acts as portfolio for student work

• Will automatically index models under concepts used

– Provide place to store student abstractions• Students can extend the ontology of entities, add new patterns

of behavior

Current Vmodel Ontology

Entities RelationshipsBasic Entities:

ThingGroup-ThingSubstanceTime-SlicePlaceProcess

Properties:AttributeNumber-attributeStateForm

Observations:Observed change

Argumentation:LawDataHypothesis

Property links:Has-AttributeDoes

Comparisons:Same asIs a kind ofGreater/less thanEquals

Configural:TouchesContainsPart ofMoves from/toIs changing

DynamicIncreases/decreasesDetermines +/-AffectsEnablesPrevents

ArgumentationlSupportsConflicts with

Curriculum Development

• Context: NSF Center for Learning Technologies in Urban Schools (LeTUS)– Partnership of Northwestern University, University of Michigan,

Chicago & Detroit public school systems

– Work circle organization for researcher/teacher collaborative development

• Beverly Miller, Deborah Rogers-Green, Adam Dorr, Carol Scafide, Kiesha Korman and Carlos Rodrigues

• Two curricula under development– Solar house curriculum (extending Marcia Linn’s work)

– Mars Survival Station (ecosystems)

– Using self-explanatory simulators to provide phenomena to explain

• Starting to be explored for use in other curricula as well

Related Work

• Quorum project (Canas, Ford, Hayes, et al)– Inspired our use of restricted concept maps

• Widely deployed in South America by IBM

– Teaching “the Giant” great idea• Never widely deployed

• Teachable Agents (Biswas, Bransford, et al)– “Teaching Betty”, “Team Betty” as motivator