Handouts are available below

Big Idea

Evaluating arguments, claims, and lab results is a science skill that needs to be taught and assessed in the NGSS as well as the BC Science Curriculum. How do you assess it? Today, I share two types of the questions I generate for labs and tests to assess the “evaluate” skill.

Two Types of Questions to Assess Evaluation

Before I get into the questions, I want you to know that I tend to assess evaluation on tests and not assignments because tests are the one task I know where students are working independently. With labs and take-home assignments, students copy off each other or get help from others and, thus, may not be representative of a student’s ability.

Now, evaluation differs depending on context; thus, I’m going to go over 2 of the most common ways I assess evaluation depending on 2 different definitions of evaluation according to the curriculum.

Definition 1: Evaluation is evaluating claims using scientific knowledge and findings from investigations. On a test, what I do is give students an opinion or idea and I ask them whether they believe the opinion or idea is true or false based on what they’ve learned. For example, on my quiz on KMT, I give this question on juicing lemons – and, yes, juicing lemons is related to KMT. “Lemons can be juiced by cutting a lemon in half and then pressing it against the dome of a citrus juicer. One day, Leo collected 15 mL of lemon juice using a citrus juicer. Leo’s friend, Brian, suggested Leo heat up the lemons before juicing them. Brian said that heating up the lemon before juicing will result in more juice being collected. Do you agree with Brian’s hypothesis?”

Now, consider other wild claims you’ve come across and put those on a quiz for students to consider. The issue is not so much whether they’re right or wrong but more of how they’ve come up with their conclusion.

Definition 2: Evaluation is identifying possible sources of error and suggesting improvements to our investigation methods. For this, I give students a lab activity to perform for which I know the exact result and they need to draw a conclusion from it. Even better if the lab is something that is counter intuitive to students. For example, in our pendulum lab, I have students measure how long it takes for pendulums of increasing mass to complete 10 swings if they all start from the same height. So, students construct a pendulum with 1 washer and swing it 10 times and then a pendulum with 2 washers and swing it 10 times and so on. Students measure the time and come up with a conclusion. Usually, students believe that mass decreases the time it takes to complete 10 swings – and they will try to manipulate their data to match their belief either by redoing parts that don’t agree. Then, I tell students the real answer – mass does not change the time. Thus, the time for 10 swings is the same regardless of mass swinging. So, for a post lab assignment, students answer one question by themselves: identify 2 possible sources of error in your lab data and explain the impact of those errors.

You might not make pendulums in your class, I get it. But consider other measurements you make – like those for density, which is pretty set for metals. You can do the same lab there and have students explain their errors.

Thanks for reading, and let’s talk science education again soon.

Resources

Handout(s):  Ep51 Handouts – Testing Students’ Evaluating Ability

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