In a responsive teaching environment, students will propose lots of ideas. Teachers attend to these ideas and then must decide how to respond. How does a teacher decide her next move? That is, which ideas should she follow up with? How does she decide which ideas are worth pursuing?

We suggest teachers make their next move decisions based on their assessment of the scientific merit of the students’ ideas. By scientific merit, we do not mean how well the idea aligns with a specific content standard, or how fruitful the idea might be in leading to students to an understanding of that content. By scientific merit, we mean how productive would this question be for leading the students towards substantive engagement in scientific inquiry. So, what kinds of ideas might be productive in this way? We suggest to teachers who are just beginning to engage in responsive teaching that they might focus on three basic criteria: clarity, causality, and consistency.

• Clarity is the easiest one, and the minimum requirement for an idea. Can other students in the class understand what the idea is? For example, in one of our classrooms, students are talking about what causes gravity. A student suggests an idea that inside the middle of the earth there is a large magnet, and that the magnet pulls people down. Now, that idea might not be scientifically ‘correct,’ but it is easy to imagine what the student means. Certainly one of our goals for students is to help them explain themselves clearly, and to look for clarity in their own and each others’ ideas. Sometimes students have difficulty articulating their ideas, so either the teacher or other students can help rephrase it to make it clearer.
  
  
• Causality has to do with ideas that are about tangible, familiar causes and effects—connections to what people experience or might experience. The word we use more often is mechanism; we want students to learn to offer ideas about how things happen or work that are mechanistic.
  
  Consider the idea mentioned above, that a large magnet in the center of the earth causes gravity. That idea is certainly mechanistic, or causal, in that students can understand that a magnet could cause something to be attracted towards it. Whether it is a valid idea or not could be tested experimentally. Students could explore whether magnets can attract parts of our bodies, such as our fingers or arms. If they find out that magnets don’t attract parts of our bodies, then students could conclude that a magnet being responsible for gravity is not a valid idea. However, the fact that the original idea is stated in a way that is mechanistic or causal provides an opportunity to conduct an experiment to test the idea. On the other hand, if a student suggests that gravity just happens, that it’s just ‘there,’ his idea would not meet this criterion. Being ‘just there’ is not mechanistic. Students could not understand how ‘being there’ could cause gravity, and certainly it could not be tested experimentally.
  
  As another one of our goals, we would like for students to offer ideas or explanations that are mechanistic. With practice, we want them to see that a good scientific idea is one that is mechanistic, one that provides a causal reason for why something happens.
  
  
• Consistency is about whether the idea is consistent with other things the students know. Although the idea about a magnet at the center of the earth causing gravity is consistent with students’ experience that magnets do attract certain things (like iron), it is not consistent with other experiences the students might have had. For example, students might remember that when they held magnets in their hands, they did not feel that there was any attraction. So, since people are attracted to the earth, their experience is not consistent with the idea that a large magnet can cause that attraction. Thus, that idea might not fully meet the criterion of consistency.
  
  As another one of our goals, we want to see students paying attention to consistency, asking themselves and each other how their ideas are or are not consistent with things they know or believe. Looking for consistency is also important when collecting data in an experiment designed to provide evidence either in support of or not in support of a particular idea. When a student makes a claim about the results of an experiment, she is looking for consistency between the evidence and the idea that is being tested. If students see inconsistencies between the idea and the evidence, we want them to resolve those inconsistencies—perhaps either by checking the experiment or modifying the original idea. The process of making claims (offering ideas about something), supporting that claim with good reasons (evidence), and resolving any inconsistencies, is a process known as scientific argumentation. So we want students to offer ideas that have the potential for engaging them in scientific argumentation.