Posts in Category: phenomena
ice melting
On hot summer days you might really enjoy a glass with ice, just because you like a cold drink. But have you watched the ice in your glass up close?
I like investigations just watching ice melt. By taking some video and speeding it up, you get to see the whole process in just a few seconds. Here’s an example where we take ice that’s made from water with red dye. This way, as the ice melts you get to trace where that new liquid goes.
When you watch the ice melt, it’s funny that it goes from the top of the glass and falls to the bottom. What makes it do this? Why did it float in the first place? What would make it sink?
There are other liquids besides water that we can’t drink, but we can still put ice in them (as long as we’re very careful and label these liquids so we don’t accidentally put them in our mouths). I decided to compare what regular (water) ice does when it melts in water compared to when it melts in rubbing alcohol (isopropyl alcohol) that you can get at a pharmacy or grocery store.
Here’s a fast timelapse of these two, side-by-side. We think there’s a lot of interesting things going on, even at the beginning before any melting has happened. We added some salt at the bottom of the isopropyl alcohol to make it a little easier to see and to make some salt water as the ice melted.
I really enjoy making these videos because then we can replay these episodes really quickly and make comparisons. But it’s also great just to see how ice melts in different ways in real time. You could make videos; or, you could write notes or take pictures or just observe and talk to others about what you’re seeing. You might think of other variations on this theme.
sun circles
It was a nice morning, and I thought it would be a good choice for me to sit in my backyard and read a book. But it’s easy for me to get distracted, and soon I was really interested in a spot of light that was on my chair:
(For more information about this great book, see:
https://www.hepg.org/hep-home/books/science-in-the-city)
I wondered what made this spot and I turned around to see how sunlight was coming through this tree behind me:
What I think is really amazing is how all of these leaves and the gaps between them are different shapes, but the light coming through makes circles. I used a white notecard to find more of them:
You’ve probably seen spots like this before, maybe without even knowing it. (Once you start to see them in a few places, you might have a hard time not seeing them!) Sometimes under a tree we say that there’s “dappled light,” but it doesn’t matter what you call it. There are funny shapes and a kind of light that photographers and artists like, all made by the overlapping circles of light like this.
Can you find circles of light like this in other places? What do you think makes these circles? Why are there so many? Are there other ways to make these sunshine spots? Could these circles be a picture of something else?
waves on a lake
On a camping trip a while ago, we had a site that overlooked a small, calm lake in the Uintas. From a perch we could toss small rocks into the lake and watch the ripples they created. Tossing two rocks at the same time made it so that we could see what happens when the two sets of waves overlap.
You might want to look at the video up close, or even pause it at certain spots to see what’s happening. What do you observe? What patterns do you notice? Where else could this happen?
light in gelatin
Some science investigations are especially fun to do at home. Playing with light and playing with jello are each great activities for indoors. This investigation prompt puts these two things together.
Here’s a video that I made at home, with no fancy lab or equipment — the perfect setting for most science-in-the-making. This is just to give you some ideas of where you can start, but there’s lots more you can play with and do.
In summary, all you need to do is make a gelatin dessert in your choice of flavor/color. Plain gelatin works great, too, but it doesn’t smell as good. When we make it, we just use half as much water (or don’t add any chilled water) and let the gelatin set in the refrigerator overnight. Then, cut out any shapes you’d like and put them on a surface like wax paper, a cutting board, or even just a clean table. Use a small flashlight or laser pointer to shine through the jello from the side, and observe what the light looks like as it goes into, through, and out of the jello. In my investigation in the video, I discovered some new things about how the light gets bent and focused; and I learned that my yellow jello lets through certain colors of light, but not others. I thought this was all really surprising and interesting, especially knowing that it was all caused by my 99 cent box of generic, lemon dessert.
Many other people do jello optics as well. Our friends at the Exploratorium in San Francisco showcase jello optics as one of their “science snacks.” Once you get started you’ll probably find other experiments to create on your own; or if you’re in a course I’m teaching you may be crafting lenses or other light bending and bouncing shapes with jello at home or in the lab.
looking up at the night sky
When the weather gets clear, it’s not only great for going out in the day, but also for going outside at night. There’s a lot of great science happening both during light and dark hours. In fact, observing dark skies is a scientific study all by itself!
Sometimes we take it for granted, but the reason why the sky is dark at night is not only because our side of Earth rotates away from the Sun, but because there’s a lack of other light as well. This tells us something about everything else in our Universe and how far away all sources of light must be and what they must be doing. (This is related to something called “Olber’s Paradox,” and it’s fun to read and think about, especially before you go outside to look at stars.) It’s also important that our own light from our neighborhoods and cities are not flooding our skies with their own light. If the canvas of the sky isn’t dark, then we aren’t able to see it contrast with dim stars.
You can measure how much extra light is in our sky by counting how many stars you can see — the more stars you see, the darker the sky must be. This is easier to do than you might think, and we’ve left some instructions below the break on this page that you can use to do this. You can compare your star counts on different dates and in different locations to see what happens to your star counts. We’ll record your star counts on this form as part of a project to analyze our dark skies locally. (Or, if you want to follow the instructions and only record the data for yourself, that’s a great project, too.)
If you’d like to share your data with an even bigger project, you can take a look here at the Globe At Night program . They have their own program and form to report your view of the sky by looking at specific constellations that they help you find. Then, this data gets compiled with other observations from all over the world. You can see some of their results here.
This is an exciting project for a few reasons. First, it’s a way to see how our own lighting affects what we see at night, which can have big implications that you might not even realize. The International Dark Sky Association shows examples from right here in Utah that you may have visited:
There’s a full list of designated “Dark Sky Parks,” here, and they include this gem in Weber County.
How familiar you are with the night sky, navigation, and even culture is dependent on being able to see stars against a dark background. But most of all, we think that it’s awe-inspiring to see a dark sky, maybe even with a view of our own Milky Way Galaxy stretched across the sky.
The first step to seeing any of this is simply to go outside in a comfortable place, let your eyes adjust, and look up on a clear night. Even if you do nothing else, just look up an imagine. You’ll start to see more than you might expect.
The other thing we love about star counting projects is that these are part of a larger collection of work called “Citizen Science” projects. These are scientific pursuits that you can help with by reporting your own data. Besides the Globe At Night program and the International Dark Sky Association’s own promotion of the program, there are completely different projects you can help with. We might highlight some of these in the future, but here are a few examples:
- Our own National History Museum of Utah features a collection of citizen science projects that could be especially relevantto you here in Utah.
- The projects showcased at Zooniverse extend more globally and even throughout the universe! (You can help categorize galaxies, observe ocean life, record migration patterns, etc.)
Whatever you do — even if it’s just for yourself — recognize that the observing and appreciating is a big part of how science gets started. Let us know what you start to see, and let us know if you have questions along the way!
Instructions for counting the stars in your sky
On a clear, dark night, go outside at a location of your choice — your backyard is great — and count the stars! Instead of counting all of them, however, you will count them as you look through a toilet paper tube. (Maybe this is why people are buying so much toilet paper these days?)
After your eyes are adjusted to the dark, hold the tube to your eye and point it in a random direction and count how many stars you can see in that part of the sky. This is a sample of the sky. Do this 8 times, each time pointing in a different, random part of the sky. Write down your counts so that you can analyze them when you go back inside.
Once back inside, you can also get your location’s approximate star count by:
- Adding up your 8 counts all together, and then
- multiplying that sum by 9 (assuming you use a toilet paper tube, because this factor describes how much of the sky you were sampling with this device).
For comparison, if you had a completely dark sky and well-adjusted eyes, you could be able to see almost 5000 stars with the unaided eye. How did your measurement compare? How do you think it would be different in different locations? (You should try other places , too, when you have the chance!)
You can also do more research on dark skies and light pollution. A good place to start is here:
where the International Dark Sky Association provides other information and tools for doing more star counts. They also describe why this is an important issue — but you might think about this yourself before you read more.
hot chocolate effect
We often imagine that good science is the kind of thing that studies the dynamics of distant stars and a cure for disease. Sure, it does work on these big problems. But it is just as focused on and important to our everyday experiences.
Here’s my prime example. This is me at home, stirring some hot chocolate. It turns out that hot chocolate can demonstrate a very novel effect that you probably have never noticed even if you’ve stirred hundreds of mugs of the beverage. Once you realize it’s right in front of you, you may be forever cursed/blessed with the tendency to tap the bottom of your mug after you’ve stirred the chocolate in.
My hope is that you would want to try this out and think of ways to investigate what’s going on. If you’re in one of my classes, you’ll probably be given this as an assignment or even as the subject of an entire lab. You would consider trying out variations to see if you can find what causes the effect: What if you used something other than hot chocolate? Or different kinds of hot chocolate? Or different mugs? Or other ingredients? By changing the conditions, you might start to narrow down what makes this effect. At the same time it can be really challenging, because changing one variable could change another; and sometimes we don’t even recognize when a variable is changing.
Something I like about this investigation is that it naturally makes you consider your own model about sound and the hot chocolate. When you decide to change something in this system, you naturally have some idea about why that may or may not work, and it’s based on what you’re imagining is happening in the hot chocolate and how you might think that sound works. The results of your test affect your model and give you insight into what test to try next. This is, in essence, how science works.
Studying the hot chocolate effect is one of my favorite science investigations in the whole world. I introduce it to students, teachers, and scientists whenever I can because:
- Once you have experienced the effect, you may be forever cursed/blessed with tapping your mug of hot chocolate to hear this phenomenon, and you hopefully will share it with anyone else around when you are enjoying your beverage. You may even start investigating the effect by honing in on specific variables and testing specific conditions.
- We often think science is about warping space and curing disease. And that’s correct, but those are just a couple of examples. Scientific pursuits are at hand in all kinds of scenarios, and sometimes you just have to look a little more closely. You might have stirred hot chocolate hundreds of times and never noticed this.
- Also, people–especially scientists–often think they know the explanation for this right away. They usually don’t. (I’m speaking for myself as well.) And why should they? There’s a lot going on here, and we should embrace not knowing right away. Simply diving into this human endeavor of science is something we should celebrate.
- And even when you understand an “answer” to this, it usually isn’t finished. One “answer” just leads to more questions, and this effect is a prime example of where this can lead you down lots of rabbit holes.
Enjoy your hot chocolate, and your science.
walk on rock
I like to walk in rocky places. Fortunately, we have lots of this terrain here in our mountains overlooking Ogden and the surrounding area on the Wasatch Front. From here in my backyard mountains (as I like to think of them), I’m looking up at rock cliffs, or maybe across a canyon at a pile of rocks, or sometimes in a creek to see the wide array of rounded rocks in the water. I think of this all as “at-home” science observations because it’s so marvelously close to where I live. It’s a good way to get out of my house, go for a walk, and observe and wonder about nature, all at the same time.
A little farther away, in the Uinta Mountains, there are other places to go on a long hike or a shorter walk. I see all of the same things I do here in my “home” mountains, but also some other interesting new observations. Often I’m walking right on top of large rock slabs at high elevation.
When I was walking in this area above Ryder Lake, I loved to see all of the high ridges surrounding me, but the ground I was walking on in this wide open, giant bathtub like basin was very flat and very smooth, as if it had been sanded. But there were also lots of big rocks that were sprinkled around on top, as though they had been dropped from above like a giant had a giant salt shaker that sprinkled really big boulders all around.
There are other areas like this one in the High Uintas, and I think they’re really fascinating and mysterious. Feeling the rock and seeing it firsthand make me that much more curious about how this all came to be. Here are my wonders:
- Why was the ground I was walking on so flat, even though the mountains around me were so high and steep?
- How did the rock slabs I was standing on get so smooth and almost shiny?
- How did this basin become so wide and flat and host lakes and ponds at high elevation, while other mountain canyons where I live are narrow with a fast flowing stream through them?
- And how did these boulders get here as though they’d been sprinkled around? Were they part of how the slabs got flat and smooth, or did they come later?
- And the more I looked at the rocks, the more I wondered about the patterns I saw inside of them: layers and stripes, pockets and crinkles, hard edges and corners and cracks. I wonder how these rocks were made in the first place.
What do you imagine happened to make all of this? Can you tell a story that helps us put all these observations together? How does it fit with other things you know about rocks, mountains, and valleys?
I like to talk to my geologist friends about what I’ve found, and they help me to imagine what happens in these mountains and everywhere else. But the most important thing they tell me is that they, too, walk in these places and study these formations and have these same kinds of wonders.
sky nuggets
A few days ago some late afternoon clouds rolled in, the winds picked up, and then stuff started falling out of the sky really violently. It was a big thunderstorm with hail.
The first thing I noticed after the storm passed is how these little chunks of ice stayed on the ground, but they disappeared fastest on the hard surfaces and stayed the longest on the soft grass and other plants:
I thought this was interesting enough, but it was even more interesting when I looked more closely at some of these hail remains:
When I saw this hail up close I noticed a few more features that surprised me. First, it wasn’t round. It looked like a tooth or a candy-corn or a mini-pyramid. And also, it looked like it had stripes or layers. I thought I might just be imagining this, or maybe this was just a random strange piece of hail. So I started looking around in the grass more. I started to find these striped “teeth” hail all over!
I expect to see layers in rock or sand sometimes, but it’s funny to see it in ice that’s fallen out of the sky. It made me wonder:
- Why are these hail pieces shaped this way, like a candy-corn or a tooth? How did they form?
- When they fell, were they pointed with the pointy side up or down? And how could we figure this out without waiting for the next hail storm? Is there an experiment we could create?
- And where did those stripes come from? Are the clear stripes made differently from the white stripes? Are these different layers made at different times, or did they come off of some other big chunk, or were they made in a whole different way?
- Why have I not noticed this kind of hail before? Is it rare? Or does it happen all the time and I just wasn’t paying attention? I thought hail was round most of the time, but maybe I wasn’t looking carefully. If there are different kinds of hail, what makes them?
Have you ever observed hail like this? Or have you seen different kinds of hail or did you make different observations of the same kinds of hail? I think there’s a lot more we could observe and wonder about. Now, I can’t wait for it to hail again in my backyard so I can go see what it looks like next time!
science at home: noticing and record keeping
Schooling in a collaborative environment with a collective vision is no small task in any time, and that’s probably ten times more apparent in the middle of the pandemic. The educational system we’re used to, in spite of owning its share of flaws, is a monumental invention and a well-designed piece of community engineering. We can’t just dump the design we’ve had and expect it to work well in another context — especially in the midst of disease, job losses, structural inequalities, and limited resources.
I wrote about how I think we should forgive ourselves and not expect so much from at-home, online education. In fact, I think that this gives us a chance to think about what we really value about education and what goals we might have in mind. Mostly, though, let’s stop expecting that anything at home can approximate what we have at school. I think that’s silly and we shouldn’t abuse ourselves trying to do more than what we can expect of the current situation. (Writing that piece helped me a lot in trying to figure out some things, and I’m happy to talk with anyone more about our big educational ideas and ideals.)
But this brings us to another question: What can we do now? What can our students do? If education isn’t the same, then what is it, especially in light of trying to get kids to engage in authentic science, its questions and practices and general engagement with the natural world? As I think about what we’re trying to do with school science, it’s clear that we want to make it more tied to authentic science; so if we move school online and at-home, how can we make sure that we’re just not moving science further away from authentic practice, wonder, and the natural world?
I got inspiration from Billy Barr, described by some as a hermit, who’s spent 50 years living in solitude in the Rocky Mountains. I like Billy, especially the fact that he admits that his lifestyle and how he does it is pretty individualized. We can’t all imagine that we would want to live like him, nor that we would would do things exactly the same as him if we were in his situation. But one thing that I really appreciated was his idea of record keeping, to keep track of something, as part of his daily routine. In his case, some things that might seem really mundane have become the basis of longterm scientific study, even though he never aimed for that.
This makes me think about our own homes. Instead of taking something that we would want to do at school and re-engineer it for all of our kids at home, all separated from one another, what if they each had their own agency to notice, make observations, and collect their own records? How can they connect with their own, personal worlds?
I think that one of the hardest parts of doing science is the beginning: How do you start? You can’t know how to start until you become familiar with something and get inside of it. In Billy Barr’s case, he started measuring snow depths in the1970s simply because it was a part of his space and because he wanted something to do. It might have actually helped that he was isolated, because it gave him a focus on his unique environment. By tracking those levels over the years, his data eventually because useful, decades later, in climate science research. He’d never intended this in the beginning; he just happened to be in the right place and mindset to collect those data.
Perhaps more important than keeping daily records, Billy is especially familiar with his environment and is especially attuned to his surroundings. Too often we ask budding scientists to come up with an observation and a question and an investigation all prematurely, before they really get a feel for what they’re doing. I think it’s important to really be immersed in and familiar with a phenomenon, paying attention to and playing with it before we can really know how we’re going to investigate it.
So, I want to suggest that our students at home can take the lead in their immersed and isolated environments. What kinds of noticings and immersings can they take part in? They’ll come up with better ideas than me — and they’ll connect better with their own ideas than with mine — but I’m thinking of things like:
- which way does the wind blow today?
- how dark is it at night?1
- how tall is the grass?
- what time does the cat wake up to eat?
- how many drips of water from the faucet are there in a minute?
- where does the sun set each evening?
- what does it smell like outside?
- what do you hear in different spaces?2
- how does your dog take a step with each of its 4 legs?
- how many blossoms are on the tree today?
- how far can I see today?
- how much did it rain today?
- how many birds do I see?
- where are there cracks in the sidewalk? what do they look like?
- etc.
I know there are more and (I think) students will come up with observations that are especially relevant to them. I can imagine that they can use those experiences to develop their own questions, in their own culturally and physically relevant spaces, and that these can be (eventually) used by a teacher or a group to develop investigations and tie to modeling.
This is simply an idea, and I’m interested to hear what others can do (or would refuse to do) with it. Most of all, I want to shift focus when we ask people to do science at home and get a better, more authentic idea of what that could mean. I don’t think we need to force it into a curriculum that we’d imagine in our school buildings. It can, and probably should, be different.
Most of all, as I’m writing this during a pandemic, when we’re all vulnerable and beleaguered, let’s be kind to ourselves and to our students. Right now it’s enough to make it through each day. Maybe that can be a little easier if we can focus on the little things that surround us.
- I’m working on a way to study light pollution. Here’s a link to a form with some instructions and other information. I’d be interested in having others try this out: https://forms.gle/YuvWRUEaZx6shx4FA ↩
- Canyonlands Field Institute, a favorite educational organization of mine, has this lesson on creating a sound map: https://cfimoab.org/create-a-sound-map/. For an at-home project, I might do something different, but I really like notion of creating a map that models what sounds are like in different spaces, and trying to figure out how to represent those. ↩
Newton’s 3rd Law
Whenever two objects collide or interact in any way, we might start to talk about “Newton’s 3rd Law.” I should say from the outset that I don’t like starting with this label, because I think we have to assemble a bunch of experiences before we really have a feel for what we’re talking about. At the end of these notes, I finally get to some experiences we can look at in class (or socially distanced across the internet). If you’re reading these notes, that’s very likely where you started. This is just meant to circle back.
Newton’s 3rd Law really bothers me. Here’s why: It’s so easy to give it a quick definition, something like “equal and opposite” or “action and reaction” or “forces come in pairs.” But because these quick descriptions are so, well, quick, it’s hard to really see the significance of them. Newton’s 3rd law tells us that there are always two bodies responsible for forces, and so there are always two forces, one on each of the objects. These forces are the “equal and opposite” forces.
Let’s consider this in more detail and test more situations.
First, let’s think about a collision, since this is the most obvious place where two bodies interact. A collision never happens with just one object. One thing has to run into the other. As that happens, both bodies are “feeling” something. It’s easy to imagine this when to two objects are comparable: two ice skaters collide, or a car runs into a tree, or one curling stone runs into another. In other cases, we didn’t think of the two bodies as colliding so much as they were just in contact with one another, but it’s the same kind of situation: I sit on a chair, or two stationary ice skaters push one another, or the tires of a car push backwards on the road. And, it could be that the forces aren’t pushes, but pulls: two tug-of-war teams are pulling on the same rope, or a child is sitting in a swing, or, even, the Earth and Moon pull one another using the force of gravity.
As we think about each of these situations, what is our model for how these interactions take place? That is, what are the pushes and pulls? We’ll start with a rope that two people hold, thinking about how the pull on one person compare to the pull on another. We can also think about the details of pushing forces, such as Adam pushing on the wall. What about other cases?
It’s hard to really collect evidence for how forces compare. What if we had some kind of spring-bumper in between colliding objects? What would we expect of these as they experienced different forces? What would you expect spring-bumper cars to exhibit as they were colliding in different situations?
In class, we consider a lot of different situations where we vary the masses of the two objects colliding (same masses or a big vs. little mass) and we also vary the speeds of the two objects (both moving towards one another or one running into another that’s originally at rest). We can predict what we think the relative forces will be.
The “spring-bumper” mechanism that I imagine is exactly what this physics teacher has setup in his own classroom. For his students’ benefit, as well as the rest of us, he’s compiled slow motion video footage into one file, and he’s also supplied some background info and access to the original data, if you so desire. This is all available here in his class notes. You can also catch the video right from the YouTubes.
There’s some amazing revelations, and I think that seeing the footage like this is just really hard to believe on a gut, instinctual level — even though Newton’s 3rd law is so easy to state! Why is this hard for us? I think it’s because we forget about the fact that we are observing both forces and changes in motion (which is described by Newton’s 2nd Law) at the same time, and we confuse these. Two paired forces in a collision can be exactly the same size, but they’ll produce very very different accelerations — changes in motion — depending on the mass of the objects experiencing the forces. We observe most directly the changes in motion, and we erroneously equate this with force. So, the mosquito that hits your windshield and the car both experience the same amount of force, but they go through much different changes in their respective motions, much to the chagrin of the mosquito.
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* For more information or for fun, you could view a classic episode from Dr. Julius Sumner Miller on Newton’s 3rd Law. Or, take a look at this PhET simulation.