On almost a daily basis, there are articles in the news that seek to provide a scientific explanation for how or why a given natural phenomenon occurred. The topic may be climate change, nuclear energy, genetically modified food or something else that impacts the everyday lives of middle school students. Students need to be able to evaluate the evidence and reasoning presented in the article. In addition, they also need to grow in the ability to develop well-reasoned scientific explanations of their own.
Critical skills that all students should develop through their study of science are the ability to develop and critique a scientific explanation. Two of the practices identified as essential for all students in the Next Generation Science Standards (NGSS) are:
- Constructing explanations (for science) and designing solutions (for engineering).
- Engaging in argument from evidence.
Katherine McNeill and Joseph Krajcik developed a framework for teaching students how to develop and critique scientific explanations. The framework indicates that a scientific explanation includes four parts:
- A claim that answers the question being studied.
- Evidence to support the claim.
- Scientific reasoning that explains how the evidence supports the claim.
- A rebuttal that considers and rules out alternative explanations.
Middle school teachers can begin the year by focusing on the first three components of the explanation. When students have developed enough experience with the concepts of claim, evidence, and reasoning, then teachers can introduce the rebuttal, which is the most complex component of the scientific explanation.
McNeill and Krajcik also recommend five instructional strategies that teachers can use to support students in developing scientific explanations.
1. Make the framework explicit.
Before asking students to develop a scientific explanation, middle school teachers should talk about what an explanation is. Teachers can then discuss what a scientific explanation is and share the framework. Many teachers find that it is best to work with students on the claim, evidence, and reasoning first. When students really understand these three components, teachers can introduce the concept of alternative claims and how to present why they were ruled out as part of a fourth component, namely the rebuttal.
2. Model and critique explanations.
When beginning work on scientific explanations early in the school year, middle school teachers may model the development of a scientific explanation for students. As students begin to work on developing their own scientific explanations, it is helpful to have students work together in collaborative groups and to critique one another’s explanations. One strategy that may prove helpful in critiquing explanations is Praise, Question, Polish. In this strategy, students comment on something they like and ask a question. The author of the explanation is then given an opportunity to polish or improve the explanation before submitting it.
3. Provide a rationale for creating explanations.
McNeill and Krajcik identified two rationales that teachers used for having students create scientific explanations. Some teachers emphasized that scientists spend much of their time developing, presenting, and critiquing scientific explanations. Because students were learning to think and act like scientists, it was important for them to spend time engaging in similar activities. Other teachers emphasized the persuasive power of well- developed scientific explanations. They emphasized the value of being able to identify and present evidence in a way that will encourage others to stand in agreement with the explanation one is presenting. Either way, teachers found that middle school students worked harder on scientific explanations when they had a rationale for why they needed to learn to create effective explanations.
4. Connect scientific explanations to everyday explanations.
Teachers found value in helping middle school students see how a scientific explanation was similar to explanations they might develop in other classes. Teachers also found it helpful to have students understand that the word “explain” is used differently in different contexts. For example, when students are asked to explain a procedure, they are really being asked to describe what is to be done. They are not really being asked to do the same thing when they are asked to explain a scientific phenomenon.
5. Assess and provide feedback to students.
Finally, McNeill and Krajcik recommend giving students a rubric that they can use to self-assess a scientific explanation. The teacher can then use the same rubric to give feedback on student-developed scientific explanations. The criteria assessed should become more sophisticated as students grow in their understanding of the components of the explanation.
The ability to prepare a well-developed scientific explanation is an important skill that deserves focused attention across the middle grades. Research has shown that focusing on this skill across the middle school grades helps students develop a deeper and more complete understanding of the scientific phenomena students study in middle school. What teachers expect students to be able to produce in the way of a scientific explanation should become more sophisticated as students have more experience with developing and critiquing them.
Amy has 16 years of educational experience in Science, Technology, and Engineering as a high school classroom teacher, department chair, district curriculum specialist and most recently supervisor for Science, Technology, and Engineering for the largest school system in Maryland. Prior to her supervisor position, she designed and delivered Professional development at that national level and has authored national STEM curriculum products.
 McNeill, K., & Krajcik, J. (2012). Supporting grade 5-8 students in constructing explanations in science: The claim, evidence, and reasoning framework for talk and writing. Boston: Pearson.
 Instructional Strategies to Support Students Writing Scientific Explanations. (2007). Retrieved from http://sitemaker.umich.edu/kmcneill/files/mcneill__krajcik_teach.pdf. p 20
 Krajcik, J. (2011). Supporting students in constructing evidence-based scientific explanations. Presentation. Retrieved February 1, 2017, from http://umaine.edu/center/files/2011/06/Bagor-presentation-Explanation-V4.pdf