MODELS AND MODELING
the practice of modeling
Modeling has been identified as a science practice that is useful for refining explanations about how something happens in the world. In science classrooms, models typically include a combination of pictorial representations and written explanations about 'seen' and 'unseen' mechanisms that describe how and why a particular phenomenon occurs.
When we use scientific modeling in the classroom, we enact a cycle of constructing, revising, and testing our models against the real world. Models play a central role in an MBI unit in that they link the real with the abstract, or the phenomenon with the important science ideas we use to explain it. The diagram below shows this relationship.
We do not think of models as the product of a unit. Instead they are a tool by which groups of students are able to make sense of ideas around a phenomenon. The practice of modeling makes students' thinking visible (to themselves, their peers, and to you), allows groups of students to work through ideas as they negotiate the model, and helps generate new ideas and hypotheses to be tested. As represented in the diagram to the right (taken from Helping Students Make Sense of the World Using Next Generation Science and Engineering Practices, p. 115), models are not merely depictions of phenomena. Instead, models are tools for students to make sense of phenomena.
Construct
Revise
Test
Example student models
Here is a great resource on models and modeling in science classrooms from the Ambitious Science Teaching group. The primer contrasts how models are used in science with how they are traditionally used in science classrooms before providing practical advice for integrating modeling in science classrooms. Pay special attention to the 'Helpful advice from teachers' section at the end!
What should be included in student models?
It's also important to give students options in terms of the explanatory elements they can choose from as they construct their models. Arrows showing connections, zoom in windows showing what is happening on a molecular level, or explanatory text boxes are important elements of student models.
Using Templates to scaffold student modeling
Choosing whether or not to provide students with a template for their models is an important decision. In some instances, a blank piece of paper provides students with more agency over how they choose to represent their ideas. In others, students will get further by being provided a template that provides a much-needed structure for their ideas. These are decisions based on the age of your students, their familiarity with modeling, and other factors.
We recommend reading A Layered Approach to Scientific Models by Fowler, Windschitl, and Auning (2020) for a comprehensive exploration of model templates. Click on the image to the right to be taken to this great resource. Their article is rich with example templates including:
Before, during, and after
Comparative
Big picture
To these we add partitioned templates, which are similar to before, during, and after templates but focus more specifically on change over short time periods.
Using a Partitioned Template is one way to support students by amplifying the focus on changes in the complex anchoring phenomenon over time. This is important since, in most cases, it is the changes that happen overtime that are most important to explain, because these involve unseen mechanisms that provide explanatory power both in the unit anchoring phenomenon and in related phenomena.
The example highlighted here comes from:
Campbell, T. & Neilson, D. (2016). Explaining ramps with models: Design strategies and a unit for engaging students in developing and using models. The Science Teacher. 83(5), 33-39. (available to NSTA members)
Constructing initial models
After students have been introduced to the anchoring phenomenon and have worked together to create their initial hypotheses to answer the driving question, it is time to construct their initial models. At this point, we like to emphasize that deciding as a group what will go on the model and how is important intellectual work and that they will be revising their models throughout the unit. Models are tools to help them make sense of the science ideas as they build their explanation of the phenomenon. It's also worth pointing out that this stage of the unit is about eliciting their own ideas, before you as the teacher have introduced any science ideas. While it's sometimes difficult not to introduce important ideas about the phenomenon, it's important to hold off until the next stage where you will be able to introduce new ideas to reason with through the tasks you have chosen for the unit. At this point, it's ok (and very fruitful!) if the groups' models are incorrect or are missing important information.
We recommend the following procedure for constructing initial models:
Explain that the groups should first discuss which initial hypothesis they heard they would like to begin with. Their task is to represent that hypothesis in a visual model. To do so, they will need to decide as a group what to include and how to include it.
Whether you have chosen to give students a blank piece of paper or one of the model templates described above, hand out the materials to each group.
If your students are not experienced modelers, it is a good idea to briefly explain and provide examples of scientific models (preferably about another phenomenon!) and point out the relevant components of the models (e.g., deciding what defines the system or boundaries, what things in the system they should include, how to show connections between things, and how to show the "unseen" forces that are making things happen).
Give the groups 10-15 minutes to complete the initial models. Walk around during the modeling to help provide suggestions for ways to represent their ideas. Remember, this is about their ideas so you should not be suggesting new ideas to include yet!
We suggest doing a share-out session to allow the groups to see their peers' initial models. For this first modeling experience, we recommend a facilitated share-out session to allow you the ability to point out the things you notice about each model. Prompt questions or comments from the class to begin to build a discussion about each others' ideas.
Have students write their group number and/or names on the back of the models so you can pass them out for model revisions mid-way through the unit!
At this point, many of the groups' models will be simple representations of what happened, but will lack the causal mechanism, or the 'why' things happened. That's ok and perhaps something to point out after the share-out session.
An example initial model of a middle school plate tectonics unit.
Revising Models
Now that they have revised their thinking through a number of purposeful tasks, it’s time to revise their initial models. This step is important not only to help drive their thinking, but as a formative assessment to see the progress the groups have made in coordinating the science ideas toward a cohesive scientific explanation of the phenomenon.
We recommend the following procedure:
Begin by asking them to review their initial model. At this point, they should recognize problems with their initial models right away!
Remind them that after today, their models will probably still be incomplete because they're only halfway through the unit. But negotiating together about what should be added, removed, or revised is important intellectual work!
Ask the groups to discuss the following questions:
What do you want to keep? What needs to be changed? What needs to be added?
Have we moved beyond simply describing the phenomenon and added what causes it?
How do the scientific concepts we’ve been studying fit in? How are they represented?
We suggest letting students begin with a new piece of paper or template after they have decided what they would like to revise. However, if time is an issue, they can also use post-it notes to note what should be changed without fully re-drawing the model.
Like after the initial models, we recommend doing a share-out session to make sure the groups' ideas are visible to others. Here a traditional gallery walk might be useful.
If students see an idea they think they should add to their models, let them! Or they can at least make a post-it note of the idea so it is not lost.
An example revised model of a middle school plate tectonics unit.
Finalizing models
As we move into the building consensus stage, we utilize models as a sensemaking tool one more time. In this case, our goal is to use the construction of the groups' final models to finalize revisions based on the last few purposeful tasks and to bring the groups to consensus on a final evidence-based explanation of the phenomenon.
We recommend the following procedure:
Begin by asking them to review their revised model.
Remind them that after today, their models should be complete and represent their final ideas about the phenomenon. Once again, negotiating together about what should be added, removed, or revised is important intellectual work!
Ask the groups to discuss the following questions:
What do you want to keep? What needs to be changed? What needs to be added?
Have we moved beyond simply describing the phenomenon and added what causes it?
How do the scientific concepts we’ve been studying fit in? How are they represented?
Is our model complete? Are all of our ideas we have been working on represented?
We suggest letting students begin with a new piece of paper or template after they have decided what they would like to revise.
Like after the other modeling sessions, we recommend doing a share-out session to make sure the groups' ideas are visible to others. Here a modified gallery walk might be useful.
If students see an idea they think they should add to their models, let them! The goal now is to have a complete representation of their explanation for the phenomenon.
An example final model of a middle school plate tectonics unit.
Putting it all together
Much of this information can be found in the NSTA commentary Using Models to Teach Science by our colleagues Byung-Yeol Park, Laura Rodriguez, and Todd Campbell. They use the following four questions to guide our use of models in teaching science:
What is the purpose of a model?
How can we develop a model?
How can we use models in teaching science?
What should we consider when teaching with models?
