Discrepant events occur when a student’s prior knowledge clashes with what’s happening right in front of their eyes. The wonderful moments created by the cognitive dissonance of a discrepant event is a powerful tool for developing inquiry skills. When what happens does not match students’ expectations, we can expect them to get curious pretty quickly.
Discrepant events are almost always exciting and engaging. But you strike teacher gold when you use them to capture students’ energy and motivation so that they actually want to learn what happened; otherwise,high power laser pointer the discrepant event simply ends up being a memorable demonstration. The power of discrepant events lies in their capacity to motivate a systematic inquiry into the why and how of what students saw vs. what they expected to see. The capacity for systematic inquiry is one of the most foundational and important skills students can learn, in any discipline. The value of the ability to inquire, rather than shut down, in the face of a discrepant event translates well beyond science.
Additive and subtractive color mixing is a great example. Most students have experience with mixing paints (pigments), so they have a foundation of understanding about what it means to mix colors. They bring this understanding with them to the study of mixing light and are quickly confronted with several related discrepant events: green and red light mix to create yellow, not brown; and when you mix all three primary light colors, you get white laser pointer 5000mw light. Here’s how to structure a lesson so that students inquire on their own to figure out why!
Go a little deeper with some inquiry into what’s going on with the relationship between light and paint.
Ask students: Why/how do we see each color? Why do we see Blue or Green? Let them struggle to explain — ask them to use words and drawings to think about how it is that we see all the colors.
Explanation: How we see color — White light contains all of the visible spectrum. When white 3000mw laser pointer light hits a material (paint, your shirt, an apple) the material absorbs all (visible) wavelengths except the wavelength we see. What we see is what is reflected off of the object into our eyes.
Get everyone started with some concrete experience. Most students think of red, green, and blue as the primary colors, but for pigment (paint), the primary colors are Cyan, Magenta and Yellow. Check your print cartridge; I guarantee it says CMY, not RGB. Now you are ready to ask students to predict and then explore and collect/record data on (pigment: CMY) color mixing.