A question on my BIO156/181 Unit 5 exam addresses Mendelian genetics and the inheritance of a trait from parents. The trait in question is inherited in a simple Mendelian manner (one gene with two alleles, one allele being dominant and the other allele being recessive.) Originally the question was about hitchhiker's thumb and involved a kind of "double negative" statement, where "lack of the thumb" was dominant. I think this wording was making it hard for students to think through the problem. I reframed the problem using the trait of wet or dry earwax instead of having / lacking hitchhiker's thumb to see if scores improved. When the wording of wet vs dry earwax was used, students scored, on average, one point higher (6/9) on the problem when compared with a similar cohort of students (the previous semester) who were given the "have vs lack" question wording. I will continue to use the wet vs dry earwax question on this exam.
Yes, unfortunately I started that question based on the examples provided. It is interesting how hard it is to think about a trait being the lack of something. It is always important to consider the wording of a question and its impact on student learning.
Wording is so important. What frustrates me is when they have the same wording in the workbook (especially with lots of practice problems) and they still ask "what does this mean" on the exam.
Double negatives are so tricky. Sometimes we have to decide which is more important: the students understand the concept and can apply it or can they maneuver the question. Unfortunately many tests theses days are examples more of the students being able to maneuver the test questions rather than demonstrate knowledge of the concept.
I love how you were dissatisfied with student performance in one area, tried a new approach, and improved student performance and infomed your instruction. Good job of closing the loop in a micro sort of way!