UCSC Sustainable Materials REU PREP: this team of scientist/engineer educators designed and taught an inquiry lab activity through ISEE’s Professional Development Program

L-R: John Davenport, Caitlin Johnson, Carolyn Gee

Venue: UCSC Sustainable Materials REU PREP

Team Members: 

Caitlin Johnson (Design Team Lead & Apprentice Instructor): Graduate Student, Physics, UC Santa Cruz

Carolyn Gee: Graduate Student, Physics, UC Santa Cruz

John Davenport: Graduate Student, Physics, UC Santa Cruz

Audience: 11 undergraduates

Activity Name:  Sustainable Slugs

Learning Goals (Author Caitlin Johnson): Our content learning goal was that learners will use concepts of diffraction to explain an observed phenomenon created by diffracting objects. Diffraction is one of the fundamental concepts behind characterizing materials, and our learners were about to embark on a summer research experience for undergraduates (REU) in sustainable materials. This concept is commonly seen in introductory physics courses across science and engineering majors, but learners often struggle with connecting the theory to the physically observed diffraction phenomena.

When creating a rubric, we broke the concept of diffraction into three dimensions, all related to the different variables that impact an observed diffraction pattern. The first dimension, the wavelength of the light, seemed to be most accessible by students. We only were able to procure two different colors of lasers (red and green) for learners to use in their investigations, but they were able to predict what would happen with different wavelengths of light based on the quantitative relationship that many of them had seen from their courses. The second dimension was related to the slit spacing and geometry of the diffracting object.

Several students asked questions related to the orientation of the diffraction pattern and how it related to the orientation of the slit (perpendicular). We had not anticipated that question or stumbling block, but it proved to be an interesting discussion point with our learners during the investigation facilitation. The requirement that the slit size need to be comparable to the wavelength of the light came up in a few of the investigations, and during our culminating assessment task I was impressed that the learners were able to explain why a diffraction pattern wasn’t seen with a green light and the small slit spacing of the DVD. In our rubric, we considered this ‘nuanced understanding,’ so it was encouraging that learners were able to grasp and apply this dimension so well. The last of our dimensions, relating to the order of the peak and the cause of the bright and dark spots, was a bit trickier and not as accessible in the investigations that we designed. One student explicitly stated during their final presentation that a dark spot is when two troughs of the wave of light overlap, but that is not the case. Unfortunately, we had to mark several scores of ‘evidence is missing’ in our rubrics since there were not many investigation questions chosen addressing this dimension. In future redesigns of this activity, I would like to see more ways to incorporate this dimension into all investigation paths and understand why the bright spots get dimmer further away from the center of the diffraction pattern.

Funding for this team was provided by: National Science Foundation (AST#1643290)