Using Phenomena in Testing

text over sand and plastic pollution: Using Phenomena in Testing

One of the main tenets of NGSS is the use of phenomena to have students discover the content. I’m new to NGSS, as Indiana just adopted the standards this year, but I’m very excited about the integration of phenomena. I’m all-in on attempting to ground as much of my instruction as possible in phenomena. I know that a lot of growth will come, but so far I’m pretty pleased with how it's going. Today I’d like to share a major success - using a phenomenon for assessment.

My PLC colleagues and I decided together to lead off our course with density, as I’m sure many of you do. We used it to build skills that support learning at all dimensions of Johnstone’s Triangle: students made observations and measurements at the macroscopic level, created tables and graphs from data, performed calculations, and drew particle view diagrams. We used density to talk about asking good questions, making good observations, applying algebraic skills to equations, and reading and interpreting graphs. At the end of a couple of weeks, I did some reflecting and felt like it had been the best course opening I’ve ever had. It was time to write the first assessment.

Using phenomena had been such a positive change that I knew I wanted to use phenomena for the test. I also wanted to incorporate Earth and Space Science in some way, as many of my students will not take ESS in high school. I had the realization that I could write a question about our oceans, which led me to considering pollution and then microplastics.

I did some research and got real data for microplastics. I found density ranges and put them into a table. We then asked questions about a plan a fictitious student made up to remove microplastics and asked students to evaluate the strengths and weaknesses of the plan by applying what they knew about density. We also provided them with fake (but realistic) data about a piece of “found microplastic” and had them do calculations to determine the type of plastic that was found. This prompt was the 3rd of 3 prompts on the test, and it was by far my favorite.

Editor Note: Readers are free to use the prompt below to create their own test questions. Because Nora plans to use the questions she created again, she has not included her assessment at this time.

A week later I used the same prompt data for my honors test, but I expanded the question to include more related parts so that the entire test was woven together with this theme of microplastic pieces in Lake Michigan. 

This was the best test I’ve ever written. My students were doing deep thinking, analysis level work, and perhaps most interestingly - 0 of my 130 chemistry I and honors chemistry I students blew off the test. They were all doing deep thinking and analysis level work, gave it a good effort, took their time, and while every now and again a part of a question may have been skipped, no one skipped an entire prompt. Making the questions visual and relatable to their life experiences, and what they hear about in the media, made the test itself more engaging.


Microplastics Prompt

Plastic is the most prevalent type of marine debris found in our oceans and in the Great Lakes. Plastic debris can come in all shapes and sizes, but those that are less than five millimeters in length (or about the size of a sesame seed) are called “microplastics.” The most common microplastic polymer types in the aquatic environment are PE(25%), PET(16.5%), PA(12%), PP(14%), PS (8.5%), PVA (6%), and PVC(2%). Lower and upper density limits (grams per cubic centimeter) of these microplastic polymer types as reported in microplastic literature are reported in table 1 below.1


Table 1: Density Limits of Microplastic Polymer Types2



  1. US Department of Commerce, N.O. and A.A. (2016) What are microplastics?, National Ocean Service website, 10/26/2023. 
  2. Environ.Sci.Technol.Lett.2019,6,551−557.