For each triangle on the website, the central component is the list of model ideas displayed near the top of the page. These are the ideas we suggest are key to explaining the phenomena at hand. They are also the closest way we have to tracking content alignment with NGSS in a model-based classroom.
Our model-based reasoning approach to learning is also student-driven. In many cases, students generate the questions. Certainly the students do the intellectual work of generating, revising, and applying the models as needed to make sense of the puzzles in front of them. So, what should you do as a teacher when the model ideas students generate do not match those listed in the curricular resources? When are the ideas or the final model "close enough"?
First, the model statements for each triangle are target statements. You should not be concerned with matching the wording exactly. Throughout the resources, in fact, we try to remind and encourage teachers to track the authentic student ideas and language in the classroom. Sometimes it can be difficult, for example, to look at the 12 statements your students have generated in the model for Natural Selection and determine how well they map to the more concise list on the website. Do your best. Part of your work as the teacher-facilitator is to help the class pare down the list.
Ideally, your students will help you to condense, revise, and add to models as necessary. Students should be made aware that the ultimate litmus is this, "Do you have the ideas necessary to explain the phenomenon at hand?" This is how scientists work with models. This is also how our minds work. We continually add to and revise models, but we pause and sort of say "Good Enough!" when they generally explain what we are trying to figure out--really whether they are "complete" or not. We aren't likely to keep pushing until a new phenomenon comes along that we cannot explain or that contradicts our model.
There are many ways to encourage students to evaluate models as you go along. (Be certain, by the way, that you are clear when brainstorming without evaluation is happening in the classroom, and when ideas are open for private or public evaluation!) Some of our teachers post "model criteria" in the classroom during their "Setting the Stage" activities in order to help students make this very decision. Is the model good enough? Excerpting Setting the Stage materials from Libbie Coleman, scientific models must:
Fit and explain all observations.
Be realistic and follow all scientific laws.
Enable us to make accurate predictions.
AND must be changed if new evidence contradicts them.
Libbie is a long-time teacher and one of the creators of the MBER resources. These are the "model criteria" posted in her classroom.
What if the students are leaving ideas that are redundant or plain wrong? What if they've missed a key idea?
As the teacher, you do have some intellectual responsibility for making certain "wrong" ideas do not persist in the classroom. You also want to be sure that models are complete enough to explain what is happening. The best way to handle these issues is through conversation about the phenomena. When a "wrong" idea first appears, it is often best to let it linger as an initial idea that can be evaluated against evidence later and removed. If you get to the end of the triangle, and that "wrong" idea persists, consider the following:
(1) Does it fit the model criteria listed above? Can I help my students to see that it does not?
(2) Will it be eliminated later without my intervention (perhaps with the phenomenon in the next triangle)?
(3) Is there a phenomenon I can introduce that will bring students to evaluate the idea?
(4) What is the danger of the wrong idea? How will it concretely cause a problem?
(5) Posting to the Forum and asking other teachers how they've handled similar problems!
If you cannot have students address the idea, and you feel it is an intellectually dangerous idea, decide how you will lead students through a conversation about why the idea is inconsistent with our scientific understanding. Some ideas are complex and the result of many lifetimes of work. Students may not have all of the background necessary, and that's OK. Model-based reasoning does NOT mean you are NEVER giving students a model idea (i.e. telling them), it means that we want students to evaluate their understanding of the world against what they see and to do the intellectual "heavy-lifting" of revising their ideas in light of new evidence.
And sometimes what you have is probably good enough, or at least better than you think! You can always return to ideas later to revise them. It's never too late!