Friday, January 9, 2015

Flipping the Chips are Down Lab

The following article was featured in Carolina Tips in the fall of 2014, the online newsletter by Carolina Biological - a vendor that sells lab supplies and equipment to science teachers. 
For science teachers considering flipping their class, a great way to test the waters is by flipping the lab. Instead of using class time to lecture about and demonstrate steps in a lab procedure, consider creating short videos known as labcasts. Students can view these labcasts prior to the experiment. Watching the steps and seeing the equipment can help minimize confusion and provide clarification. Additionally, the use of labcasts can save precious class time for the actual experimentation and post-experimental analysis.

Teaching natural selection with the Chips Are Down lab

In the evolution unit, the Chips Are Down lab (which is a student favorite) does a wonderful job simulating natural selection. In this lab, students experience how populations change and generate a wealth of data to analyze (Fig. 1.).
Students play the role of predators and exert a selection pressure on a population of butterflies made of differently colored construction paper. The prey are placed on a multi-colored cloth background (Fig. 2); some of these butterflies naturally camouflage on the background, while others are easily spotted. The student predators take turns eating the prey by picking up the first butterfly they see. The predators eat a certain number of prey, then the game is paused to allow the prey to reproduce. Rounds of predation are followed by recovery of prey. After a few rounds, you see certain colored prey going extinct, while others increase in frequency (Fig. 1). The students witness natural selection in action and frequently cite this lab as the activity that helped them to understand this abstract concept.
The problem is the written instructions are somewhat confusing, no matter how many times they have been revised. Merely reading the steps does not clarify the procedure; students actually need to see it in action to fully understand it. In the past, I've typically done a round of predation and recovery with the entire class in order to help students visualize the steps. While this demonstration has been helpful, it is time consuming and limits the amount of class time available for repeating trials, troubleshooting, and data analysis. In addition, the post-lab discussion typically must wait until the next lesson.

Figure 1   Frequency of different colored prey after generations of predation.

Figure 2   Image of a multi-colored background. 

I've solved these problems by creating a labcast demonstrating the Chips Are Down lab. In this short video, I explain and demonstrate the procedure and address the commonly asked questions. Students are required to watch the labcast prior to the lesson. I set aside only a few minutes at the beginning of the lesson to answer questions; this time is much shorter than the demonstration and Q&A sessions of previous years. After the change, students were able to execute several rounds of predation, perform calculations, and discuss the conclusions, all within the same lesson. With the saved class time, students were even able to test and compare data generated from different backgrounds. All of these changes, made available through the labcast, only helped to improve student understanding of natural selection.
The relative ease and low cost of making videos, coupled with the potential gains of leveraging this technology, make a compelling case for flipped learning. Labcasts allow you to smoothly transition to flipped learning in your science classes. These videos can clarify lab procedures, save precious class time, and improve student learning.