Modelling in science lessons: Are there better ways to learn with models?

School Science and Mathematics, Dec 1998 by Harrison, Allan G, Treagust, David F

Student Modelling Abilities

Students are poorer modellers than teachers expect, and younger secondary students usually do not look further than a model's surface similarities. Grosslight, Unger, Jay, and Smith (1991) studied student-expert modelling abilities in terms of students' beliefs about the structure and purpose of models. They classified many lower secondary students as Level 1 modellers because these students believed there is a one-to-one correspondence between models and reality (models are toys or small incomplete copies of actual objects), models should be "right," and items are missing because the modeller wanted the model that way. Students also did not look for ideas or purposes in the model's form. Some secondary students achieved Level 2, in which models fundamentally remain realworld objects or events rather than representations of ideas, models are incomplete or different depending on the context, and the model's main purpose is communication rather than the exploration of ideas. Experts alone satisfied Level 3 criteria, believing that models should be multiple, models are thinking tools, and models can be purposefully manipulated by the modeller to suit epistemological needs. Some students fell into mixed Level 1/2 and 2/3 classifications. Because the levels are derived from the ways students described, explained, and used models, the levels also provide useful information about the status of students' conceptual development.

Concept-building Analogical Models

All the models described in the typology are concept-building analogical models, because they represent aspects of actual science objects and processes. Analogical models range from "concrete" scale models (like model cars and boats) to highly "abstract" theoretical models (like magnetic fields and the kinetic theory). As observed earlier, inexperienced modellers who can understand pedagogical analogical models like a model heart or eye should not be expected to understand magnetic field models without much more experience and help. Yet even elementary and middle school science textbooks introduce and use the magnetic field metaphor and rarely explain its origin or meaning. Students should not be expected to understand theoretical models simply because curriculum materials and teachers use them in descriptions and explanations!

A concrete-concrete/abstract-abstract continuum for classifying the cognitive demands of models is useful only if it encourages teachers and writers to think about the modelling experience and expertise of their audience. Grosslight et al. ( 1991 ) found that most students up to and including 10th grade are Level 1 or Level 1/2 modellers; that is, they are concrete or occasionally concrete/abstract modellers. These students believe that a one-to-one correspondence exists between the model and reality. While these students see differences between each model and reality, they cannot give reasons for their ideas, nor do they search for reasons to explain the obvious differences between the analog and its target.