Structured skepticism in the everyday science classroom

Experiment with adding food coloring to hot and cold water
Experiment with adding food coloring to hot and cold water
My 3rd period class added food coloring to hot and cold water

I love the observational experiment where you put a drop of food coloring into hot and cold water. I first encountered this lab in 2017 at a STEMteachersNYC+AMTA computational modeling in a physics workshop with Joshua Rutberg and Emily Pontius. Why does the dye spread out so much slower in cold water than it does in the hot water?

When I asked my students this past week, they worked through various possibilities. Interestingly, their first guess (across all my class periods) was that the hot water was less dense, and the fact that…

A big upgrade to your science class’s conservation of energy lesson

Photo by Vitaly Taranov on Unsplash

In the fall of 2008, I was a senior in college. Lehman had just collapsed and financial havoc abounded. At the time I lacked a framework to understand what was breaking and why.

As a physicist, my mental models were always built on conservation laws — that is, quantities whose total amounts never change. The Law of Conservation of Energy says that the total energy in the universe is constant, although energy can transfer between different types. For example: when a plant photosynthesizes, the light energy from the sun is converted into chemical energy in the plant. …

New research on an old idea

co-author: Amanda Valenti

Typical force diagrams from our physics first classes, to predict and explain change in motion

Of the hundred or so physics teachers that we (Amanda and Elissa) have encountered over the years, almost every single one believes that physics should be the first science class that all high school students take. When we ask our biology, chemistry, and earth science teacher colleagues, they agree: physics concepts are foundational and set up ninth-grade students for success later in other scientific disciplines. This article discusses: (a) why physics should come first, (b) why more schools aren’t doing it yet, and (c ) what we can do about it.

So let’s begin with (a) why…

It’s imperative.

An old New York Regents Physics exam — but not the first! (Thanks to Keith Sheppard for sharing it.)

I chose to study physics in college because I wanted to explain the universe. I succeeded in the physics major because I was told — over and over, explicitly and implicitly — that I belonged. (I didn’t know at the time how rare this was for a woman in a university physics program.) But despite these boosts, the exclusionary social structures of academic physics still took their toll on my mental health. At the time, I didn’t know why.

A decade later, now a high school physics teacher (having left a successful hedge fund career to teach in…

Color perception is strange. For example: red light looks red and green light looks green, but when red and green light come into your eye from the same source — well, then it looks like yellow light. (This is called additive color.) When I teach physics, biology, and psychology, the textbooks all explain THAT it happens this way, but they don’t show HOW it works. So I constructed a lesson to help my students work it out for themselves. I couldn’t find this content anywhere online, but it’s pretty straightforward to derive. Here goes.

I love the idea of rock, water, tree. I will teach it to my 3-year old, who's only now getting the hang of rock, paper, scissors. I do think the directionality of what conquers what is really not that obvious, though, because it depends on so many factors. In the image at the top, you said: "Tree and Rock caught in an ongoing struggle. Though the eventual victor is clear." I honestly can't tell without a time-lapse which one is going to win.

When I was younger, my father asked me what's stronger: concrete or plants. In the short run, he said, newly poured concrete can impede a plant's growth, but in the long run, plants can find their way up through the cracks. It's a never-ending dance, as long as we can stop making so much concrete at some point.

Photo by NeONBRAND on Unsplash

I was trained to teach in the era of inquiry. In the science classroom, this meant that we couldn’t just tell students something was true. Instead, I was told, teachers created the circumstances that would inspire students to ask questions and construct their own understanding. In a nutshell: textbooks = bad; lecture = bad; hands-on = good; collaboration = good.

In my experience, though, it is much more nuanced. I’ve come to believe that all modes of knowledge acquisition are valid. Sometimes you need your students to play with lab supplies in order to generate testable predictions. Sometimes you need…

Display output from a simulation I designed to help my students visualize 1-D motion

Almost every STEM teacher I know said a version of this last spring when we went remote: “It’s too bad we can’t do our in-person labs, but at least we have online simulations!” I shared this sentiment too, but there’s a pernicious implication: that simulations and experiments are interchangeable. They are not. I am separately drafting a longer blog post about the interplay between direct measurement, computer simulations, and reading authoritative sources in the STEM classroom. …

There are a number of useful frameworks for thinking about equity in the classroom, but…

National Cancer Institute (Unsplash)

My (virtual) school is closed for MLK Day, and I’ve been taking the time to reflect on equity in my classroom. In particular, I’m thinking about a frequent question I get from educators when I attend or facilitate a workshop: ​

​“Is there a list or toolkit to help me teach for equity in STEM?”

My first response is, “It’s not that simple.​ I do love checklists; I love to be able to say I did something ‘right.’ But equity work is a non-monotonic journey, and there is no single roadmap.

​That said, it still helps to know where to…

Photo by Sigmund on Unsplash

I grew up in the ’90s. My first computer was monochromatic, with no internet access. I was overjoyed when we finally got Windows 95 and I could learn to play Minesweeper. Now I teach coding to students who watched Youtube as toddlers and got smartphones in middle school. If you plan to teach students how computers work, then you need to know how your students experience technology. Only then can you make the connections that will enable them (and you!) to build on prior knowledge.

Here’s what my students believed at the beginning of this school year.

Misconception 1: It’s…

Elissa Levy

I teach physics and computer science in East Harlem, New York. I aim to engage.

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