Classroom Stories

At Play in the Classroom for Thirty-Five Years: Recollections and Recommendations for Keeping Our Spirits—and Our Students—Soaring

Scott Hildreth is Professor of Astronomy and Physics at Chabot College, retiring from the full-time faculty next spring after 35 years.  He’s worked with NASA on numerous projects, from writing about the first images taken by the Hubble Space Telescope in 1990, to analyzing the latest pictures from the James Webb Space Telescope. He worked on NASA’s SOFIA, the Stratospheric Observatory for infrared Astronomy, an amazing 747 equipped with a 100″ Infrared telescope in its fuselage that helped to discover water on the moon.

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Retirement is looming. Each day ticking by comes with a thought that I might not ever give that specific lecture again, and with a nagging feeling that I still—after more than 30 years—didn’t perfectly nail it. And with that thought, each day ahead becomes even more important, bringing butterflies to my stomach, and questions like: What can I do differently this time? What can I do to really make an impact, to help make the next class even more effective?  

And writing this, a similar question arises: What could I say to you all about teaching that would be relevant and helpful? Ultimately, teaching is such a personal thing, even if our curriculum is the same. Our institutions are different, our classes are different in size and shape and time and location, our students are different, and, most of all, each of us is different in how we teach and what we want to emphasize. What could I possibly share with you from my experiences that might be useful?   

I think Pablo Neruda had the best response: “Every day you play with the light of the universe.” And that’s the key. Play. Have fun. Find a way, every day, to enjoy and treasure what we do. Thinking back, where I’ve had the most fun in my classroom career comes in three “flavors.”  

First, in creating assignments that generate enthused participation by transforming our students into teachers. My favorite astronomy homework involves giving students surveys and quizzes to take home, where they know the answers but must query their willing (and sometimes unwilling) participants first and then explain the correct answers. Capturing what they did, what resources they used, and whether they were successful is where they gain credit. And astronomy gives us a universe of questions that are perfect for this kind of assignment, including asking why seasons occur, and whether people think Earth is hotter in summer because it is closer to the Sun (it isn’t—it’s farthest​ on July 4th!), or what zodiac sign was really​ behind the Sun on the day they were born (spoiler alert: it probably isn’t the one they read in the newspaper!), or why astronauts in orbit are really falling, even if they look like they are floating (be prepared for most folks to say, “Oh, that’s because there is no gravity in space . . .”).  

These participation assignments are enormously fun. Even after 30+ years, having students tell me how they struggled to explain why their Sun signs are different to their significant other, or how gravity really works to their grandmother, is often hilarious to read, and makes grading 40+ papers much more tolerable. Students like knowing the answers, like being the “expert,” like being able to share something with family that they have learned. Many share that the assignments gave them a reason to talk with a faraway family member. By becoming the teacher, they must learn the material at a deeper level. My meta-goal is met, and I’m smiling as wide as the moon while entering grades into my Canvas gradebook. 

My second flavor of fun comes from changing the mindset of students about who does science. This is done by emphasizing the many accomplishments of women and groups currently underrepresented in STEM, and in academia in general. I start both my astronomy and my physics classes by asking students to picture scientists in those fields—to describe who they “see,” what characteristics those imagined people might have, and where those images might have been fostered. Invariably, students have pictured berobed, bearded Europeans peering through telescopes or more than slightly quirky Caucasians in white lab coats, mostly men, often reflecting wonderful characters like that of Christopher Lloyd’s Doc Brown from Back to the Future or Bill Nye “The Science Guy.” For my engineering physics students, Einstein was always a popular choice, and a few students might have heard of Richard Feynman. Still, most don’t picture women as scientists; although, that is changing positively. When I started teaching, women were perhaps 10 percent of the PhDs and faculty in STEM, and today those numbers are higher: 40 percent of STEM PhD’s and 30 percent of faculty are women (Nina Gray, Inside Higher Ed, June 13, 2023). 

After that initial assignment at the start of the term to picture a scientist, I start off subsequent classes with a quick portrait of someone else doing astronomy or physics or engineering. It is great fun to see the students begin to change their own perspective about who does science. Sharing a photo, a biographical sketch, a quote, or a YouTube video takes a few minutes from each class—precious time, to be sure. But after seeing people who look like themselves, students do seem to pick up on what unites us as scientists—focusing on being curious about how the world works, being creative with experiments to explore that world, being patient and careful and persistent—rather than focusing on what on the surface might seem to be different. When I have surveyed my students about what they liked the most from my classes, invariably they share their pride in knowing of so many people contributing to science from around the globe, and especially of people who look like themselves.  

My third flavor of fun comes from intentionally giving students a chance to play in class by challenging them to work together toward a common goal. I create an assignment in an online quiz tool and give it a 10- or 15-minute time limit before deploying it to the class. They must then work in groups around a single shared computer to finish. Only one student logs in for the team, and only one answer comes from the team, so they have to agree before the enter key is pressed. Teams race the clock—and each other—to finish with the highest score. I have fun acting as a play-by-play announcer relating their progress in real time. But far, far better is seeing and hearing how students react to the challenge, with loud shouts of glee when the right answer is selected, and audible groans when they are wrong. Students who know the right answer will teach their teammates. Students who are unsure will argue about physics or science. Quiet students who might not say much at all during regular lectures come out of their shells when the competition starts. The classroom is noisy, turbulent, and full of smiles. I marvel at seeing an entire class actively learning and having fun while they do it. We’ve seen in recent literature how including “gaming” can increase student engagement, and I can attest to its value.   

Whatever subject we teach, however we teach, wherever we teach, don’t doubt we are making a positive difference in the world. We plant these seeds of learning in our students’ minds but don’t always get a chance to see how those sprout and grow and blossom (especially at the community college level, where students are gone or transfer in a year or two). We must have faith that those seeds, properly planted and watered and bathed in the light of learning, will sprout, one day down the road, whether we are there to see it or not. I hope to see some of that growth in my class, but even if I don’t, I have faith the students will leave knowing more about how their world works, and how much fun it is learning about that world.  

(If readers would like to see some of the assignments mentioned above, or get more details, please feel free to email Scott at [email protected]


Classroom Stories: How to Handle Cheating in Online Courses

By Ana Larson

This week, we have a guest post by Ana Larson, co-author of the Learning Astronomy by Doing Astronomy workbook, from the University of Washington. 

First, an introduction: twenty-two years ago (1998), as adjunct faculty, I developed an online course for Seattle Central College (SCC), which was Seattle Central Community College (SCCC) at the time. Online courses were just starting to become more available, and the learning management systems (LMS) were quite rudimentary compared to what we have today. I taught the online Astronomy 101 every quarter, every year, up until the 2020 Spring quarter, which is when enrollment at the college dropped.

In addition to required textbook reading, this online course consisted of three assignments each week: posting to a graded discussion board (and responding to other posts), a web research essay, and a lab-like assignment. As the years passed and the LMS became more sophisticated and included many more options for instructors and students, I added tutorials and short quizzes to prepare students for these assignments. 

This past decade has seen greater numbers of students enrolling in online courses, becoming better at self-motivation, and getting assignments in on time. However, there have always been those students, roughly 10-20 percent of the class, who just did not want to do the steps needed to learn the material. 

At first, this took the form of plagiarizing content from the Internet, primarily Wikipedia, but other sources were used as well. These instances were fairly easy to catch because the wording of the answers was obviously not in the student's voice. In these early days, some students copied and pasted material directly, including the links to other websites! Over the past few years, however, cheating has been harder and harder to catch, due mainly to websites like CourseHero and Chegg.

In an effort to help you discourage cheating in your own online/hybrid classrooms, I've listed my three best practices to discourage cheating in my online course below:

1) Give explicit information: The very first assignment that students had to submit was a graded quiz on the content of the course syllabus and the policies and procedures of the college. Extra emphasis was given on the college's honor code and on what, exactly, cheating included. My syllabi included explicit examples of what constituted plagiarism and the consequences when unreferenced direct sources were used. In the last five years or so, students could use up to three outside sources, but those outside sources needed to be properly referenced using correct MLA or APA format. Students were given examples and helpful web links.

2) State consequences: Students were told that they could get a 0 on an entire assignment even if only one answer involved plagiarism, which was the most common way of cheating in the course. I also outlined what was acceptable when students worked together, which I encouraged. In practice, if students were working on an early assignment and only a few of their answers involved cheating, I gave 0s for only those answers, with the caveat that any future instances would result in a 0 for the entire assignment. 

3) Immediately follow up: I interacted directly with students via course email and discussed why they got the grade they did. Most of the time, students were allowed to resubmit the assignment. I can think of only one or two examples where students did not respond to an email and continued plagiarizing. Those students failed the course.

Cheating is always upsetting, in any course, but in Astronomy 101, we have a unique opportunity to redirect students who cheat "by accident" by giving them the benefit of learning these important lessons without suffering from long-term consequences.


Classroom Stories: T-5...

By Stacy Palen

This fall feels weird. Really, really weird. Watching the pandemic erupt at higher-education institutions all around the country has filled me with anxiety: for my students, for my colleagues, and for myself. I feel very lucky that my University is primarily a commuter campus, so we are insulated from at least some of the pressures that are occurring at other places.

These are emergency times, and so I try to remember to be a little kind to myself. I’ve learned at least eight new kinds of software and picked up rudimentary skills in half a dozen fields that I never expected to need, like music editing and network maintenance. I don’t feel competent at any of it, but it’s unreasonable to expect that of myself. I’ve had just a few months of self-directed learning…in the middle of a global pandemic and civil unrest.

In times like these, it can be really hard to pick up your head and look forward to the “after-time.” But there will be a time after COVID. And I’m already finding things that I want to pull through into that time. Zoom office hours, for example. Would I have ever bothered to learn how to do that if not for the pandemic? Now that I’m setting up office hours for my students, it strikes me as an obvious thing that I will want to do for all my non-traditional, commuter students in the “after-time.” An introductory video to post to Canvas before class begins every semester is also a good idea, even for a face-to-face class! And weekly discussions, where students can ask and answer questions about the topics of the week—these don’t have to be confined to class time. I’m embarrassed that I never thought about these things before…but I was busy. Teaching.

This week, I am polishing up my “prep” on six courses to teach online for the first time in my life. (SIX! Yikes! Our enrollment is through the roof…we are all teaching overload…) I anticipate that next week, there will be some “fires.” Lots of things will not go as planned. Lots of things that seem like great ideas now will seem incredibly naïve later. It’s important for me to recognize that there are a whole lot of things that I have no control over at all.

We’ll see how all of this goes. I have been telling our students (in the introductory videos) that we are having ADVENTURES. As I write this, I am five days out from the first day of the semester. It feels very much like waiting for a rocket launch, with the same kind of hopeful uncertainty. I’ve done as much preparing as I possibly can. Now I just have to push the button and see what happens.

Best of luck to all of you. I hope you find some time to reflect, as you go along, about things that you will want to keep doing in the “after-time.” I’m sure there will be lots of great papers to write, about online teaching and learning, after the emergency is over. I look forward to reading all of them, and writing some of them.


Classroom Stories: The Problem of Students at Home

By Stacy Palen

I don’t know about you, but I have learned more about my students’ living situation in the last six weeks than I have any right to know. I learned that one of my students was homeless and living in her car. I learned that one of my students is living in his parents' unfinished basement with his wife and two children. I learned that two of my (senior-level physics majors) didn’t have computers or laptops of their own, and have always done all of their schoolwork on campus. I learned that several of my students have children and live in studio apartments (and I know what those children are studying in THEIR online classrooms). I learned that one of my students has two very young special needs children who refuse to wear anything but “Underoos” when they are at home in the house, even if mommy is meeting with her professor on Zoom.

And I learned that a whole lot of my students do not have reliable internet access. Of course, I suspected that already—because late last summer, a Facebook friend posted an article about students writing essays on their phones because they lack access to the internet in their homes.

A second friend who teaches English composition at a community college commented that she has a unit on “how to write an essay on your phone,” specifically for this reason.

Back in September, that sent me down a little rabbit hole to this blog post from 2018 which summarized a report from the US Department of Energy.

The take-home message is that while nearly all children ages 3-18 have a computer at home (94%), only 61% have access to the internet.

My University made what I consider to be absolutely heroic efforts to loan technology (tablets, laptops, and desktops) to students who did not have it. For weeks, they kept an office open on campus so that students could come and borrow whatever was available.

Many students were able to take advantage of this, but in the end, there was not enough to go around. (There is also a food pantry which has now moved to three locations off-campus.)

I thought a lot about all of this while I was (rapidly and unexpectedly) preparing to move my classes online. I thought about all of these problems for students:

  • Lack of internet access.
  • Having to share bandwidth with their school-aged children and their spouse working from home.
  • Having to share space with children and a spouse who is maybe not working from home.
  • Hunger, and the plain fundamental stress of major life changes brought on by a global pandemic.

And then I tried to think of the best way to ensure that this unprecedented situation “did no harm;” I wanted students to still be able to learn and make progress if they had the mental bandwidth to get it done. These problems were the primary driver behind my decision to make all of my classes asynchronous.

While I feel a deep sense of loss from not interacting with my students in real time, I’m convinced that this was the best decision for the majority of them. Many students “handed in” their homework in the dead hours of the night. Many students sent me emails at those times as well. Many students thanked me for shifting to asynchronous teaching, although some complained that they “were left to learn it all on their own.” It’s a fair criticism, especially since none of these students actually CHOSE an online course!

After I made this decision, I saw a number of articles from more experienced online teachers, who promoted the idea of asynchronous online classes. And several colleagues (here and at other institutions) reported that they tried to have synchronous classes, but attendance dropped precipitously, and they wound up shifting to asynchronous instruction.

As I think ahead to how I might best organize an online class in the next few semesters, I’ll keep these limitations for students very firmly fixed in the front of my mind.


Classroom Stories: Cheating and Exams

By Stacy Palen

We are just past finals here at Weber State, and we have been having a lot of discussions about how the transition to online learning went. Among those discussions is a big piece about student cheating. This was prompted by a faculty member who has taught the online astronomy course for a long time (27 times!) and has usually proctored closed-note exams. During the second half of this semester, those exams changed to open-note exams taken at home (presumably!) without a proctor. The average of student course scores rose 8%, and for the first time ever, no one earned a “D” or failed the class.

Clearly, this was not a controlled experiment. There are several possibilities for why student scores rose, which are not mutually exclusive:

  • Students who are uncomfortable with going someplace new to take proctored exams were more comfortable at home.
  • Students who are normally overwhelmed by a closed-book exam did better with an open-book exam.
  • Students cheated with one another by sharing answers.
  • Students cheated by looking things up online.
  • Students used a “service,” such as “Take My Online Exam” or “Online Class Hero,” or something similar.
  • Something else we haven’t thought of yet.

Figuring out what’s going on here, and why, will take more data, and probably some more experiments. We feel compelled to figure it out, because we want to maintain the integrity of the profession, and we want to help guide students to be better people.

Fighting against cheating can be draining. I recall a professor, for whom I was a TA in grad school, who carried out quite sophisticated statistical cross-correlation analyses of the in-class multiple-choice tests in order to catch people cheating on exams. He seemed to enjoy the challenge. I did not, and I found that spending so much mental effort on distrust really damaged my ability to find joy in my job. (Not to make it all about me…but I think students benefit when I’m full of joy, rather than furious.)

I take a different track. Even in my face-to-face classes, I give take-home, open-book, open-note, and written exams that students have several days to work on. I came to this solution by focusing really hard on what I actually want students to know or be able to do.

I don’t actually care if students can recall things; I care if they can figure out things. I also care to give them feedback about their reasoning. Consequently, I don’t give multiple-choice exams. All by itself, that makes cheating a lot harder. (Yes, it’s a gigantic pain to grade 120 final exams by hand. But it’s also a gigantic pain to run sophisticated statistical cross-correlation analyses, and change them every time the testing software changes.)

I don’t think students will ever not have Google (or something similar) at their fingertips, so it’s fine with me if they look things up. I write an exam that presumes that they actually do have Google, or the textbook, at their fingertips to look things up. Making this assumption lets me ask questions that are a lot harder to figure out, and therefore a lot harder to Google directly.

I do care that they “attend” class (for a certain pandemic value of “attend”), so on the exam, I ask several questions that are trivial if they’ve actually been in this class for this semester, but are impossible if they haven’t. (And I vary my lectures and materials accordingly.) This has the added benefit of automatically penalizing students using a test bank or an online service; they can’t get those points, and I don’t have to do anything special about it.

But the most important thing I do is try to make the exams personally compelling. I write a story for them, and then I drop them in it. For several years now, I’ve used a “zombie apocalypse” narrative. (In the post-COVID world, that might not be the best choice!) I used to drop them on a desert island.

In the future, I might try having them imagine they are teaching their kids about the sky, or they’ve been abducted by aliens, or that a time machine has transported them to the deep future. The common feature underlying all these scenarios is that they are on their own. I think the story matters; it makes the material feel relevant (even if they know zombies aren’t real), and it gives them an incentive to try to solve it themselves.

This semester, in the abruptly online experiment that we were all thrown into, I found that I had little to change about this practice. I had to think a little harder about the fraction of “attendance” questions that I wanted to ask, and what made for a fair question of this type. (I specifically referenced Astronomy in Action videos instead of our in-class lecture.) In my class, the average on the pre-COVID midterm was within a few points of the average on the post-COVID final, and the overall course average was just over 75%, which is where it usually is.

There are so many tools now, and so many different ways, to carve up a class into compartments that teach or test each content area, skill, or attitude; take a look at them, and figure out which ones will do the best job for the things you care about. Be sure to start by asking yourself this important question: What is it that you want them to know or be able to do? What are the deeper values you bring with you to the classroom?

Then, figure out how to design your assessments to reach those goals and teach those values. This may be overwhelming this semester, but as you look ahead to future semesters, you may find that you are changing a lot of things anyway. Changing the way you write your exams may save you the time and effort you currently spend on arranging proctors or catching cheaters, which will ultimately make it harder and less rewarding for students to cheat.

 


Classroom Stories: It’s a Learning Experience!

By Stacy Palen

I remember when I was in school, things would occasionally go badly, or at least unexpectedly, and a teacher would often say “It’s a learning experience; it builds character!”

Well. Here we are in the midst of a global pandemic, building character all over the place!

My university is in finals week, and I’ve just finished grading my astronomy exams for both Astro101 and the Junior level cosmology class.

It’s a good time to reflect on a few things.

First, I started with the driving directive that I would “do no harm.” I took note of the scores for each student when we were all sent home and decided that this would be the lowest grade that the student could earn. I felt that this was only fair since an online class is not the same experience at all. If they had wanted an online class, they would have signed up for one!

As it turns out, about 75% of the students improved their score (some only slightly), while 15% of their scores dropped only slightly—not enough to matter in the final letter grade. That left me with a handful of students (10%) who reverted to their earlier score. These were clearly students who eventually stopped handing things in altogether; a couple of them let me know their very good reasons for doing so.

I think those results are interesting and would love to know if others had similar results in their classes!

Second, what an amazing opportunity this is to identify which things students can learn just by reading, and which things students need real live instruction in order to learn! Maybe I would call this “learning by conversation” to distinguish it from Learning by Doing. We were sent home right at the transition from the Solar System to stars, so all of stars, galaxies, and cosmology was carried out by asynchronous online instruction. I noticed the following in my Astro101 exams:

  1. My students basically understand the H-R diagram; they can add new stars to it and identify regions and stellar properties like temperature. However, they do not understand evolutionary tracks, and the misconception about stars evolving ALONG the main sequence remains, even though it is explicitly addressed in the text. I do not have this problem when I teach the topic “live.”
  2. Special and general relativity are full of misconceptions. It seems as though reading about it reinforces what they already think is true, even if what they are reading is actually saying the opposite of what they already think. They miss the subtleties and re-interpret the text to match what’s already in their heads from Star Trek or wherever. For these topics, they absolutely need to have someone see their foreheads crinkle in confusion and give them the chance to ask questions as they have them.
  3. Every misconception about the expanding universe is still there, even though the text tries hard to counter this. And the videos. And the simulations. This is fascinating. These misconceptions persist in part because we didn’t get to do the hands-on “balloon universe” activity (can your students find balloons in their house? I don’t have any). But partly, it’s because they don’t get to hear someone ask the question “but if everything’s going away, doesn’t that mean there has to be a center?” and get the answer 8 or 10 times in a class period.

I’m sure there will be more examples as I process, and think about how to learn what I can from this unplanned experiment. I’d love to hear what you are noticing about this idea of “learning by conversation.” It will help me think about tools to develop over the summer in case we are all teaching and learning online again in the Fall.


Classroom Stories: Electron Transitions in the Atom

By Stacy Palen

Before we all were sent home because of COVID-19, my class completed a short in-class activity that was intended to prepare them for the study of stellar spectra. This activity can also be done by students taking online courses, although the big advantage of doing them in class is that it gives such insight into where students are struggling with the material!

This activity is all about transitions in the atom. I thought it was interesting that many of my students did not know about energy level diagrams (which I didn’t really expect), but I was surprised to learn that a fair percentage of them had never even heard of the Bohr model of the atom.

After listening for a while to the discussion, I was reminded that a fair number of my students are concurrent enrollment; they are actually high school students who are taking this course to fulfill their science credit. We can argue about whether that’s a good idea (I do not think that astronomy is a good substitute for chemistry).

The fact remains that they are taking my course and I need to teach them about a subject that is completely foreign to them.

This activity introduces the concept of electron energy levels, emission, and absorption. I struggled a bit here to introduce the idea that in order to make an upward transition, the electron has to get energy from somewhere, and therefore the “rest of space” will have less energy in it. I didn’t want to introduce Kirchoff’s laws yet, and they hadn’t yet seen an absorption spectrum. But they got the point, despite my unhappiness with the imprecise language I used.

Click here to access the activity for yourself and let me know how it works for you!


Classroom Stories: Light as a Wave

By Stacy Palen

Typically, I lecture about light as a wave by showing students images of waves and describing wavelength, frequency, and velocity. Then I tell them that wavelength and color go together; that light of a particular color has a particular wavelength.

However, when we would get to the Light and Spectra activity, it was clear that they had not fully internalized this information. Given that I’m not lecturing at all this semester, I invented a short activity (which can be accessed by clicking here) that unpacks this relationship a bit.

The activity uses an LED light tower that I happen to have. You can find this specific one here, but the activity could be adapted for use with spectral tubes or images from the internet.

I cannot darken the room this semester, so being able to adapt this activity made it indispensable. I also could not use the spectral tubes for my students because they simply weren’t bright enough to see. I wound up using the online images from the light and spectra lab. Without this activity students would not have been able to use their spectrum glasses in the classroom at all!

Oh, and in case you were wondering, no, it doesn’t work to try to project the spectrum tubes using the document camera.

Despite the difficulties in using the online images, student performance on the light and spectra activity was better than in the past. They also seem to have acquired a clear understanding that color and wavelength are related.

You can check out the activity yourself by clicking here!

 

 


Classroom Stories: More Ruminations on a Theme: Fermi Warm-Ups

By Stacy Palen & John Armstrong

This week, we have a guest post from a colleague at Weber State University. John Armstrong is also teaching in the inadequate classroom. He is experimenting with a way to fill the time while he figures out what’s changed about the A/V situation since the last class two days ago… 

Thanks to some intermittent multimedia issues in my new “temporary” classroom, I’m forced to get creative with the first ten minutes of class every day. So, I start by giving a Fermi problem to my students. I ask the question and they can work on the answer while I jiggle cables and try turning things off and on again.

Physicist Enrico Fermi was famous for posing seemingly unsolvable questions that he would then proceed to solve with a few back-of-the-envelope calculations. The most famous of these—how many piano tuners are there in the city of Chicago—requires some educated guesses about population, the popularity of pianos, and the diligence of their owners, but you get surprisingly close to the “correct” answer without knowing much of anything.

In astronomy, this tool has been leveraged in the Drake Equation to estimate the number of civilizations in our galaxy, proving that even when you can’t know some of the parameters you need to measure, you at least have a framework for study. The first three terms of this equation—the number of new stars formed in the galaxy, the number of these stars that form planets, and the number of Earth-like planets in each system—were largely unknown when I started my studies in the mid-nineties. They now have pretty good estimates. We are now on the verge of an estimate of how many planets can evolve life, which is something that could happen in the next decade or so.

But when I reached this point in my class, going from a simple Fermi problem to the Drake Equation seemed like a heavy lift.

I’ve always started the semester with a formal activity on estimating the number of pebbles in a jar. We measure the volume of the jar, remove a few pebbles and systematically measure their volumes, and then divide the two. The amount of agreement between the groups is surprising.

But thanks to my A/V woes, I’ve started asking a question every day. How much does the mass of humans increase each year? How far does a bumblebee travel in a day? How much food energy do you consume in a year? And each day, more and more students seem to dive in. Better yet, some of them have come in after doing some of their own estimations. How many bricks are in their house? How much electricity do they consume every year? 

The answer to the last question turns out to be surprising: It’s about ten times the amount of energy that you eat in food.

While I’ve always seen the value in Fermi problems, their routine application is giving my students extra practice and increasing their numeracy. And they also seem to be sparking my students' interest in their own questions.

I can’t wait to get to the Drake Equation!

—John Armstrong


Classroom Stories: Another Way to Do the Phases of the Moon

By Stacy Palen

The phases of the Moon are one of those topics that has been extensively studied by the astronomy education research community and is well-known to be more complex than most people think. There’s the change of perspective from Earth-view to space-view. There are multiple motions at once (the rotation of Earth and the Moon, and the revolution of the Moon around Earth). There’s the issue about light rays always traveling in straight lines and not bending. It’s complicated.

Last week, I pulled an old phases-of-the-Moon activity out of the archives, which can be accessed by clicking here, for my students to complete in addition to the activity, “Studying the Phases of the Moon” from the Learning Astronomy by Doing Astronomy workbook. This is not an appropriate activity for Learning Astronomy by Doing Astronomy because it requires students to have Styrofoam balls that have been colored black on one half. (I can’t make the classroom dark, so I can’t use the traditional “balls-on-sticks” approach.) But one thing that I like very much about this activity is that it leads them to figure out how to (approximately) tell time by the Moon, which means that I can ask them a question about it on my zombie-apocalypse midterm—insert evil laugh here!

The activity also asks them to consider the phases of other objects, such as the phases of Earth as seen from the Moon, or the phases of Deimos as seen from Mars or Phobos. Carrying the concept of phases away from Earth seems to help cement the idea that this is a phenomenon that is all about the relative location of the light source and the observer.

I followed this activity the next week with the “Studying the Phases of the Moon” activity from the workbook. I was interested to notice that students finished the activity in record time and were much better prepared for it. The two activities worked well together to really build their picture of how the phases of the Moon actually occur.


Classroom Stories: Energy and Kepler’s Laws: A Surprise for Me about Where the Difficulty Lies

By Stacy Palen

Recently, my students worked on the “Working with Kepler’s Laws” activity from the Learning Astronomy by Doing Astronomy workbook. In this activity, students learn about ellipses, consider the “simple” version of Kepler’s second law (a planet travels faster when nearer to the Sun and slower when farther away), and run some numbers for Kepler’s third law: P2=a3. To my surprise, Kepler 1 and Kepler 3 brought almost no questions from the students (aside from “Am I doing this right?”). It was Kepler’s Second law that brought the most substantive questions.

Over and over they asked “Yes, but WHY does it go faster when it’s closer?”

I used this question as the basis for a whole new activity.

Approaching this question as an energy problem, I had the students throw a ball straight up in the air and make pie charts representing how much kinetic energy, gravitational potential energy, or thermal energy the ball had at various points in its trajectory. Then they threw the ball to a friend and made similar pie charts (in this case the velocity is never zero, so the kinetic energy is also never zero). Then I had them consider a planet in orbit around the Sun and make a third set of pie charts.

Wow! This was so much harder for them than I expected!

First, it turned out that pie charts are a concept that most (but not all) of my students have in common. Who knew?

Second, we ran into the issue about where to put the “zero” of gravitational potential energy. This information was in the Background section, so it was invisible.

Third, we faced our biggest issue: Convincing students that when they threw the ball straight up into the air, the ball had zero speed at the apex of the trajectory. That alone was a 20-minute conversation!

Finally, even though I told them to describe what happens to the ball between the moment after it left their hand to the moment before they caught it, many students turned all the energy into thermal energy. I’ve edited the activity to try to correct these problems and will use it again in the fall in search of perfection.

Despite these problems, I was very happy about the conversations that I overheard as I moved around the room. Some students were completely unfamiliar with the conservation of energy. They made progress simply by learning how the energy transformations occur for a ball thrown in the air!

Other students rocked that part but were stuck when the questions about orbits showed up; this was often because they drew the Sun at the center of the orbit instead of at a focus. What a great opportunity to correct this problem!

Finally, some students spent a very long time arguing about whether they needed to account for energy lost to thermal energy in our current Solar System.

Overall, I was pleased by what I learned about how they think about energy as well as how well they grappled with this material. And I’ve now set them up to have a spark of recognition when they learn about planet migration later in the semester. This activity is a work in progress, but I will definitely try it again!

You can access the activity by clicking here!