Signal to Noise Ratio in Learning

I think those of us who are educators would agree that, since the start of the pandemic, our students are more distracted than ever. In fact, I think most of us, educators or not, feel more distracted than ever.  There are health concerns and trying to keep ourselves and our families safe. There are political divides and threats to democracy. There is inflation and economic concerns. There are floods and fires and billions of dollars of damage because of weather-related events. Our phones bring news of all of this turmoil directly into our daily lives. Even when we aren’t looking at our phones, we might be thinking about looking at them. Or they might be notifying us that someone is texting us or commenting on our latest social media post. Add to that the distractions that have always been with us. Maybe there’s a lawn mower running outside our window. Maybe we’re thinking about our grocery needs or yesterday’s conversation with our best friend. Maybe we’re feeling a little under the weather and our ears are blocked or our nose is running. In any case, the world is noisy, full of distractions that impede our ability to focus on what is going on right in front of us.

Our students might be physically in the classroom but there is often all kinds of noise getting in the way of them hearing what we are trying to say or engaging in the activities we have planned. I used to think mostly about getting my students to understand what was going on in the classroom. The only kind of noise I thought about addressing was the challenge of the complexity of the content of the particular class. Of course, this is an important consideration. But I am increasingly aware that the first obstacle to understanding is the noisiness of students’ lives and the world around them. It might be useful to think of the first of our educational tasks to be the amplification of the signal of our educational messages so that it stands out amidst the noise of all the other information that students are bombarded with in their daily lives.

My current obsessive hobby is astrophotography, capturing images of objects in the night sky. Photography is all about capturing light to create images but at night, there is very little light. So in astrophotography, we have to amplify the light that we do capture. The challenge of this is that when we amplify the light from the objects in the night sky, we also amplify the noise that we get from our various tools. For example, to capture enough light for a deep sky object to show up on our camera’s sensor, we have to take long exposures of a minute, two minutes, even ten minutes and more. When a camera’s shutter is open for that long, the camera may heat up and cause amp glow to affect some of the pixels on the sensor. That’s an example of one kind of noise. There are many different kinds of noise that can appear in low light conditions and we have a variety of techniques to mitigate them.

One technique for noise mitigation is stacking multiple images of the same object on top of each other. This technique works because the light signal from the object is steady while noise tends to be random. So we can amplify the steady signal and remove some of the random noise. This process improves the signal to noise ratio (SNR) in our images. How might we use this idea in education? Perhaps we move away from the idea that because we as instructors have lectured on particular content or had students read something about that content, we have “covered” the content. Helping students learn content might require repetition. For example, if I’m teaching students about variables in programming, I might start with explanations about variables, move to activities using those variables, and give assignments related to variables. But then when I start talking about if statements (or whatever my next topic is), I might repeat some of the things I “covered” in the previous lesson about variables so that students understand variables in this new context. The repetition would take different forms depending on discipline but I think the important point is that we stop thinking about “covering” content and instead think about how to amplify the signal of the important content above the noise of everything else.

Another way we might amplify the signal we want students to learn is to make sure they have easy access to that signal. One tool that we use at Plymouth State for that access is Canvas. Every instructor is required to post their syllabus on Canvas but many people don’t use the tool beyond that. For example, instead of putting their assignments on Canvas so students have easy access to the details whenever they might be working on the assignments, some people only hand out paper assignment descriptions. Some people only describe the assignments verbally in class. If we are thinking about amplifying the signal that is our assignment description, we would most likely do all three of these things–hand out a paper assignment description, talk about the assignment in class with a verbal description, and post the assignment on Canvas so students have access to it any time they can get online. The repetition makes it more likely that the signal will cut through the noise. Some people might post their assignments online someplace other than Canvas. This introduces a new kind of noise because now students have to remember where each instructor posts class material. Some people post their assignments on Canvas but in a relatively disorganized way. We don’t have a standard Canvas template that we are required to follow. I won’t argue that we should have a single template but I think we might agree that by having lots of different organizational strategies for Canvas sites might mean that we are introducing a kind of noise into our classes that students will have to navigate as they try to engage with their four or five classes per semester.

I am finding it helpful to think about ways to improve the signal to noise ratio of the content of my classes compared to the larger world of our students’ lives as a way to improve student learning. I’ll be curious to hear others thoughts about this way of thinking about teaching.

In June 2023, I captured the featured image of Fleming’s Triangular Wisp, part of a supernova remnant in the Cygnus constellation, approximately 1500 light years from Earth. The image is a stack of 33 five-minute exposures for a total of five and a half hours. For many years since its discovery in 1904, the object was called Pickering’s Triangle, named after the director of the Harvard College Observatory, despite the fact that it was discovered by Willamina Fleming who worked at the HCO and discovered many deep sky objects during her career.