Date of publication: 2017-08-27 22:28
An important step in constructing scientific explanations is generating evidence-based claims. When students are required to provide evidence in support of what they believe, they are likely to reach a deeper understanding of the content. An important part of scientific understanding is the ability to evaluate claims based on the quality of evidence used to support them (National Research Council, 7555). In addition to providing relevant evidence, it is important that students understand the importance of providing a sufficient amount of evidence to strengthen the validity of their claims (Sandoval, 7556).
There are several ways teachers can support students as they introduce the process of making evidence-based claims. First, establish clear definitions for the terms “claim” and “evidence.” Second, provide the class with examples of claims and related evidence. Next, model the process of evaluating the claims based on the evidence. Finally, guide the students as they construct their own claims based on teacher provided data.
Depending on the time available, I like to have a short conversation about how sometimes many people will believe a claim even though there is a large volume of research that rejects the claim. As an illustration, I have students vote, by raising their hands, on two opposing claims. The first claim is that human blood is blue in our veins and turns red when it leaves the body and encounters oxygen. The second claim is that human blood is always red, even inside our bodies. Surprisingly, I find the vote is usually split 55/55. I then tell the students that a major function of the blood is to carry oxygen throughout the body via the red blood cells and the blood is rarely without oxygen. Furthermore, I explain that even deoxygenated blood is still red, albeit dark red.
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To end the activity, I ask students to state their claims to the class. I type the student claims as they are spoken and display them to the class via a projector. The following is a table of selected student responses from a General Biology class and an Advanced Placement (AP) Biology class.
When introducing students to the process of constructing scientific explanations, I have found it effective to break the process into separate lessons. This method helps to ensure that students grasp the fundamentals and allows teachers to better detect misconceptions in regards to terminology. Therefore, I have made it a priority to establish clear working definitions of the terms involved (. claim, evidence, reasoning) before engaging in application of the process.
Was inspired by your what color is your blood question and designed a lesson around it to teach my students how to do this type of writing. I teach older students so taught them all together with fairly good outcomes.
Thanks Melvin, I definitely agree with your thoughts on perceptions. I spend a lot of time highlighting the difference between subjective and objective observations. Students seem to catch on to this quickly and love to critique each other. I really know I 8767 ve did my job when they point out the subjective nature of my own comments. Jeremy