Category Archives: Science

One day last spring, near the middle of April, one of my students noticed a web of some kind high up in one of the trees on our playground. Soon, a group of children had gathered and they began to discuss what had caused the mysterious web.

I had a pretty good idea what it was, but I kept my thoughts to myself. It’s not all that common for children to come across such a unique and fascinating phenomenon. I wanted them to practice thinking of possible explanations. It’s hard, sometimes, to hold your tongue when you have the knowledge your students are seeking. But if you want them to learn not just the facts but also the processes that produce those facts, you have to allow for some struggle. Most students concluded that some kind of spider had made the web. One student thought that it could be part of the tree.

A few days later, I noticed that there were a few more webs in the same tree. One web was within my reach. I decided to break off its branch, so that we could observe it in the classroom.

Right away, the children saw that inside of the web was a group of caterpillars. At this point, I said, “Oh! I think these are called tent caterpillars.” We did a little bit of research and determined that there are two varieties of tent caterpillar that live here in DC. I printed pictures of those two varieties, which the children compared to our caterpillars. Everyone agreed that we had captured eastern tent caterpillars (Malacosoma americanum).

We kept the caterpillars for about two weeks. They spent most of their time hiding in the middle of their web, but they occasionally ventured out in groups, crawled around, expanded their web, and munched on leaves. We expected, based on our research, that they would consistently emerge at specific times of day. However, we were never able to identify a reliable pattern. They often came out shortly before lunch, but not every day.

As we continued to research eastern tent caterpillars, we read somewhere that they can live in various types of trees. I suggested that we could do an experiment to see if our caterpillars would eat different leaves. We started by adding a leafy branch from one new tree. The caterpillars didn’t take a single bite from it. One student observed that those leaves smelled “spicy,” and suggested that, “maybe they don’t like spicy leaves.” So we put in two other varieties of leaves, neither of which smelled spicy (according to our budding scientists). The caterpillars ignored those, too. We were skeptical, and rightfully so. I later learned that we had been misinformed in our research; it seems that eastern tent caterpillars only live on one family of trees.

The children also observed that there were little black balls in the caterpillars’ web. I was sure it was waste, but most of the children thought they were eggs. We took some out and put them in a small container, in order to test the egg hypothesis. Nothing happened, of course. A week later, we observed one of the caterpillars pooping. “I think it’s laying an egg,” one student proposed. I explained that it’s moths and butterflies that lay the eggs, not caterpillars. That convinced everyone that we were dealing with poop, not eggs.

Out on the playground, I combed over the caterpillars’ home tree and found something that looked more like tent caterpillar eggs: a bump on a branch that was likely caused by an insect of some kind. I broke it off and brought it back to the classroom. Alas, nothing ever came out of it; whatever was in there had probably already hatched, perhaps years ago.

The caterpillars’ waste had built up rapidly, and it had begun to stink, so we decided it was time to let them go. We released them one by one, carefully placing them back onto the tree where we had found them.

We saved four caterpillars, in the hopes that they would form cocoons, and two of them did. A couple of weeks later, we had two healthy-looking lappet moths. They weren’t very exciting as pets. They changed positions at night, but nobody ever saw them move. We tried putting the cage in a dark closet, hoping that it would awaken their nocturnal instincts. Still, they stayed put. When we took them outside to release them, I was able to get them to crawl onto a slice of orange. The first rested there for about a minute and then took flight. It flew directly to the bark of a small tree. A group of children followed it and one of them exclaimed, “It’s camouflaged!”

I don’t know if this particular set of activities is replicable. But, I wanted to share it because it demonstrates the potential richness of learning experiences that incorporate nature. Plants and animals can stimulate children’s wonder and curiosity like nothing else. Whatever outdoor space you educators and parents have access to, I encourage you to make the most of it.

My class is in the middle of an investigation of outer space right now. A pair of recent news stories has intensified their interest. This past weekend, a very bright meteor lit up the skies over D.C. One student was lucky enough to have seen it from his back yard. (Yes, I am jealous.) A couple of weeks before that, researchers from CalTech revealed evidence that there’s an undiscovered planet in our solar system, far beyond the orbits of the other eight planets. This new-to-us planet, dubbed “Planet Nine,” hasn’t been observed, but something big seems to affecting other bodies gravitationally.

There aren’t many clues as to what Planet Nine might be like. So I challenged my students to create their own renderings. Here’s what they came up with.

“I think it might have a tail. I think it might be green.”

“I think it has dots. And stripes.”

“This is a double planet…”

“I think it has fire balls…”

“It has circles…”

“I think it has my name…”

“I think it’s rainbow colored.”

“This is just a planet. It doesn’t have anything.”

Who knows; maybe one of them will be close. Of course, nature itself may very well reveal something even stranger.

This past summer, I introduced my class to a series of science activities using mealworms. I had expected it would capture my students’ interests for just a few weeks, but it developed into a deep investigation, which captivated us for most of the summer. I’d like to describe some of what unfolded.

First, a few tips. Mealworms are easy to care for. You can buy them at most pet stores—they’re meant as food for pet reptiles, and they’re usually stored in a refrigerator until they’re sold. They can eat a variety of foods (including polystyrene, apparently), but I recommend oat bran, because it serves well as both bedding and food. The only other thing they need is water, which they can pull from fresh vegetables. I used baby carrots, because they’re cheap, easy, and long lasting.

An Introduction

Before introducing my mealworms to the class, I let them grow fairly large—about an inch long. I hoped students wouldn’t have to wait long before seeing changes.

I didn’t tell the children what was going to happen. In fact, I didn’t even use the word ‘mealworm’ at first. Instead, we began by discussing larvae. I asked what they knew about caterpillars and butterflies (which was plenty). I pointed out that a caterpillar is one kind of larva—that there are many other types of insects that begin as larvae before changing.

Then, I pulled out the mealworms (“larvae,” I called them) and we started observing. I scooped them out of the terrarium and onto plates for closer inspection.

I asked children to speculate on what kinds of insects our larvae might turn into. Hypotheses included: butterflies, beetles, ants, bees, and flies. One student suggested that I get a lid for the terrarium, because he expected the larvae to change into flies.

Metamorphosis

Soon, we began to see changes. There was dead skin in the terrarium, evidence that larvae had been shedding their skin. We also noticed the appearance of small, half-curled little critters that moved very little, if at all. I suggested that some larva might have turned into pupae—the transitional stage between larva and adult insect. (A caterpillar’s chrysalis is a pupa, too, I pointed out.)

About a week later, we saw our first beetles. The beetles were white at first, making them difficult to spot in with the oat bran, but they slowly changed to brown or black.

Studying Individuals

At this point, the children were very excited. I wanted to find a way to extend our study. We hadn’t yet been able to study individual larvae, because they were unidentifiable and they moved around in the terrarium. So I decided to have each student care for a single larva, giving them a chance to observe their own mealworm’s development over time. I punched holes in the lids of small plastic containers. Children prepared their containers with oat bran and carrots, and then they each chose a larva from the terrarium. They named their new pet mealworms. (This was near the height of the Frozen craze; naturally, a full quarter of our mealworms were named Elsa.)

For the following two weeks, children checked on their mealworms daily. They made (mostly rough) drawings of the mealworms each day.

In that two-week period of time, most of the mealworms progressed from larva to pupa to beetle. When students asked to take their larvae, pupae, and beetles out of their containers, I tentatively consented, emphasizing the need for kindness and delicate care when handling live animals. There were some accidental drops, and children weren’t always gentle. (They discovered that they could get pupae to move by “tickling” them.) But the mealworms proved resilient. None of them escaped, all but one continued developing, and we had a lot of fun playing with them.

A New Generation

By this time, our original terrarium had produced twenty or thirty full-grown beetles. After each had emerged from its pupa, I had moved it into a second terrarium. Now, I presented children with a new possibility: perhaps the adult beetles (in the second terrarium) had laid eggs.

I scooped piles of oat bran from the second terrarium onto plates and the children set about looking for eggs. Although we never found anything that looked like an egg, our failure prompted a variety of thoughtful explanations from students: perhaps the beetles hadn’t yet laid eggs; perhaps the eggs were too small to see; perhaps the eggs were camouflaged. One student, drawing from prior lessons on mammals, suggested that beetles might not lay eggs. “Maybe they’re mammals,” she posited.

However, after more careful observation, we did find a fresh set of tiny mealworms! They weren’t easy to spot, but after patiently watching piles of oat bran, we often noticed very slight movements. With careful digging, we were able to locate and isolate these new larvae. My students were so enthralled with searching for these tiny critters that we continued hunting for nearly two weeks.

If you’re looking for a science activity to try with young children, I recommend getting mealworms. They’re cheap, easy, and fun. And with the right guidance, they can present great opportunities to practice thoughtful, creative, early scientific thinking.

After a recent snowfall, my class ran some experiments with snow, salt, and sand. Science experiments have been prevalent in my classroom for many years. But until recently, most of them we carried out as large-group, teacher-led activities. I redesigned my science center this year, hoping to give children more opportunities to set up their own experiments.

Many students came with some prior knowledge about what salt does to snow and ice. We live in Chicago after all; snowplows are a familiar sight. I challenged some assumptions, however. I asked, “Are you sure? How do you know?” As a group we briefly talked about how experiments can help us see if something is true, and also help us learn new truths.

Getting Things Ready

In preparation, I filled containers with snow and stored them in a freezer. If it’s in a fairly large container, the snow won’t melt for hours after it’s removed from the cold. Then I poured sand and salt into separate condiment dispensers. And I made small signs with the words ‘salt,’ ‘sand,’ and ‘just snow.’

My instructions were somewhat vague: fill two containers with snow, do something different to the two containers, and then watch what happens. I wanted children to make their own decisions about what to compare. I expected that we’d end up with a wide variety of arrangements, and we did.

Minutiae and Minor Setbacks

Things did not go quite as I had planned. (They rarely do.) At first, I had children filling small plastic test tubes with snow. I reasoned that it would be easiest to observe our results in test tubes, on a rack. But it was pretty difficult for the children to get snow into the small tubes. They became frustrated.

On day two, I adjusted by setting out little round containers instead. It was harder to tell how much snow had melted, but students were able to set up their experiments much more independently.

Another hiccup: children had trouble distinguishing between words on the tiny signs. I knew this would be a challenge, but I also thought it would be a nice way to incorporate functional reading skills into a fun activity. Alas, the words ‘snow,’ ‘salt,’ and ‘sand’ were too similar for most students to distinguish without significant support, which distracted them from main goals of the activity. I should have included tiny pictures of saltshakers, sandy beaches, and snowflakes.

Also, many students disregarded the word ‘just’ and placed ‘just snow’ signs in each of their containers. As a result, most containers were labeled as ‘just snow,’ even if they contained salt or sand, and I ran out of ‘just snow’ labels.

Perhaps the toughest challenge in designing activities for my new science center has been anticipating which minutiae have to be in place for an activity to succeed. It’s hard to think like a young child—it’s a big part of my job—and I’ve learned to expect that I’ll overlook some notable detail each time I roll out a new activity.

Results and Conclusions

Although things didn’t go as smoothly as I had hoped, this was a successful activity. Students were able to set up experiments independently, they were highly engaged, and they had fun.

We ended up with more “salt and snow” conditions than any other type, probably because it’s more fun to add more ingredients. The experimental conditions were not very well controlled, of course—nothing was precise. Still, most students walked away convinced that salt melts snow, and uncertain about the effects of sand. When students disagreed about their results, I used it as an opportunity to talk about the commonality of disagreement among scientists.

Most importantly, we saw how a simple comparative experiment can help us learn about the world around us. The scientific method, in its simplest form, is accessible to young children. All it takes is a little bit of scaffolding.

I taught my students about outer space last month. We learned many facts about planets, stars, and more. But while science education for young children often emphasizes the factual knowledge, I want my students to do more than regurgitate. I want to foster an early understanding of scientific methods, because it’s not the products but the processes that set science apart.

When we talk about science, I often remind my students that scientists try to learn new things. That means they come up ideas—hypotheses—that might be wrong. Sometimes, scientists must change what they think.

Pluto offers a nice example. Every year, a few students enthusiastically declare that Pluto is no longer a planet. But if I ask follow up questions, they usually reveal that they think Pluto changed in some way—that it was a planet until something happened to it. Of course, the only thing that changed is in our heads. Scientists used their instruments to learn more, and that changed how they think about Pluto.

To give my students practice making their own hypotheses and changing what they think, I set up an activity with meteorites. I put out sixteen rocks and told them that some had come from outer space and crashed into the earth. I challenged them to come up ideas about which ones were from outer space. They weighed the rocks with our scale, and looked at them with various magnifying glasses. I asked many open-ended questions to flush out students’ reasoning.

A handful of hypotheses emerged. Some students thought that meteorite must have “holes” (craters) like the Moon and Mercury. Some thought that the meteorites would have to be a certain color, perhaps black. Some looked for scratches caused by crashing into the earth. And some students were more vague, saying things like, “I just think it looks like a space rock.”

On the third day, I asked students to start recording their ideas on a chart. Each rock had been assigned a letter. Students circled ‘yes’ or ‘no’ for whether they thought each rock was a meteorite. On subsequent days, I reminded them that they might want to change what they think, and many did.

When I was ready to wrap things up, we sat down to have a summary discussion. We began by making a graph that represented how many students thought each rock was from outer space. There was some consensus, but much disagreement.

Then I pulled out my computer and together with the class did some (staged) research on what meteorite scientists have learned, because they have looked at many more rocks than we have, and they have done experiments on them. We learned two pieces of useful information. First, meteorites are heavier than most rocks of the same size. Our rocks varied in size and some of our small rocks weighed little enough that they wouldn’t register on our scale, so to avoid confusion I moved on. Second, because meteorites have iron in them, they will stick to strong magnets. We pulled out some strong magnets and tested each rock. We found two that were magnetic. (They are, in fact, meteorites; I purchased them here.)

Now, I don’t really care if my students learned that meteorites are magnetic. That wasn’t my goal, so I didn’t stress that point. Instead, I emphasized the way new information had changed what we think. I asked, “What did you think before? What do you think now? Have you changed your mind?” One or two students maintained their previous positions. If they were scientists, I told them, they would need to learn more about meteorites. Then maybe they could make the rest of us change what we think again.

We recently had a visitor in our classroom. Emily Conover is a physicist and science writer who earned her Ph.D. in high energy physics. She offered to teach my students a little bit about particle physics and to set up an exciting experiment for our new science center.

I talk to my students about scientists frequently. Whenever there’s an opportunity, I ask them to think like a scientist. Sometimes I wonder if they ever ask themselves, “Why does Joe talk about scientists so much? Can’t he just answer our yes-or-no questions?”

I also wonder what our youngsters picture when I start talking about a scientist. Is it something vague? Is it a man with glasses, pouring liquids into beakers? Having a real life scientist in our classroom gave us a better idea of what a scientist can be like. Emily shared some photographs of some of the instruments she helped build, and of the laboratory in Chooz, France where her experiment is carried out.

Particles and Electrons

Emily also taught us about particles. We learned that everything is made up of very tiny things, much too small to see. Bigger things you can break apart. We can break a cookie, for example, into smaller and smaller pieces. But when it’s as small as a particle, you can’t break it up anymore. That lesson was pretty abstract for our youngsters, but it was a nice introduction.

Next, she taught us about one particle called the electron, which sounds a lot like the words ‘electric’ and ‘electricity’ because when we use electricity, we send tiny electrons through wires.

Knowing that electrons can go through wires, we asked the scientific question: what else can electrons travel through? To test it, Emily and I set up a small light bulb, attached to a nine-volt battery, with a break in the wire. We explained that the light bulb would only turn on if the electrons from the battery could go all the way around to the light bulb.

Note: we took a minute at this point to talk about safety. We certainly don’t want children going home and playing with wires. We explained that electricity is very dangerous; our experiment was safe only because we used very small batteries.

We then set the children loose in our science center and let them experiment, sending electrons into each object and checking to see if they made it all the way to the light bulb. I set out a variety of objects—different shapes, sizes, and materials—and I invited the children to pick other classroom objects or toys to try.

In a matter of minutes, a group of students had discovered that metal seemed to be key. Word spread quickly among the rest of the class, but everyone was eager to test it out nonetheless.

A few metal objects did not work: a non-stick pan and some metal objects with paint on them. They offered opportunities to reevaluate our assumptions, which is the type of thinking I aim to facilitate. Scientists often must change what they think, as I regularly remind my students.

One student was particularly interested in seeing whether electrons could travel through a chain of objects.

We purchased most of the materials that we needed at RadioShack. It took some time to put things together, but it was fun. I’ll hang on to them and use them again in coming years.

I want to thank Emily for thinking of an excellent idea, for carrying it out beautifully, and for taking the time to visit us. My students were lucky to have you.

One of my big goals for this school has been to expand science education in my classroom. I’ve always given my students a pretty healthy dose of science, but much of it came in the form large group activities and discussions. Every year, we learn about many scientific topics, and we run many experiments as a group. But we lacked a dedicated space where children could independently engage in scientific activities on a regular basis. So I rearranged my classroom and made room for a new science center.

A typical preschool science area contains a few basic tools: magnifying glasses, a balance,  rulers, a tape measure, magnets. Children enjoy using these tools, but I’ve found that their novelty wears off rather quickly. Unless they’re given new purposes, they’re soon used used as props in imaginative play scenarios more often than as scientific tools. I don’t have a problem with that–in fact, I left some of our old magnifying glasses with the kitchen toys, where I would often found them–but I wanted to have a set of tools set aside exclusively for scientific activities. These are the items I purchased:

• Magnifying Glasses. Probably high up on any list of scientific tools. I got a few different kinds of magnifiers. These standard magnifying glasses have both 3X and 6X magnifiers on them. However, it takes a little bit of skill to focus them. Many students prefer to use these little “bug boxes” or these “pre-focused” magnifiers. I usually set them all out.
• Rulers and Tape Measures. Which type probably doesn’t matter much. I got these translucent rulers and I already had some small tape measures that work well.
• Scale. Instead of a balance, I decided to get a scale. Young children tend to want to fill balance buckets with as many objects as possible, which becomes a bit of a distraction from the concepts they’re designed to teach. A scale has the advantage of injecting numbers into our science activities. My students can still compare the weight of two objects; it just takes an extra step. (I have a number chart on the wall in the science center, for students to reference.) It was tough finding a good scale. I settled on this digital scale, which has a grams setting. Most digital scales that use ounces or other units show a decimal point, which confuses young students. A digital scale that’s set on grams usually doesn’t include decimals.
• Small Containers. I gathered a variety of small containers, which we’ll be using to run experiments. Most were old plastic containers I had in storage, but I also purchased these plastic test tubes.
• Tweezers. We might want to handle some very small objects at some point. I wasn’t sure if the kids would be interested in these tweezers, but they love them. They want to use them for everything, so I remove them when we’re handling fragile objects.
• Stop Watch. I’m still unsure how exactly we’re going to use this, but I want to give my students some experience measuring time. I purchased this timer because, as with our scale, it doesn’t show decimal points.

Preparing Activities

Acquiring new tools was the easy part. The challenge has been preparing a steady series of interesting activities for my students to engage in. There are a lot of early-science resources available, but they often have limitations. Most of the activities I’ve found fit in one of two categories: (1) run an experiment that is largely teacher-directed, or (2) offer various items (often from nature) for students to examine. Teacher-led experiments we do carry out regularly, but they don’t fit well in a learning center that’s driven by student choice. Exploratory examinations are going to be a regular fixture in our new science center, but they lose their appeal if offered too regularly, and I don’t want to stop there.

I want my students to manipulate things and make simple comparisons. I want them to interact with objects, come up with ideas, and then test their ideas. Young children can understand the scientific method at a basic level; they’ve shown me consistently. They’ll learn it even better if I give them abundant opportunities to practice. It’s going to take some creativity and some hard work, but I’m looking forward to the challenge. Stay tuned for updates on my recent efforts.