Ms. Caitlin's Science Update!

Pre-K: We had a new animal visit the classroom this week. This animal goes through a big change in its life, from a tiny egg hatching into a worm-like animal called a mealworm, The mealworm eats and grows and sheds its skin, until it finally goes into a pupa stage, where it stays very still and doesn't eat. Finally, the adult emerges as a beetle. It is similar to how a caterpillar changes into a butterfly. We got to observe the adult beetles, and students had a chance to let the beetles crawl on their hands with their tickley feet. 

 


Pre-K SpEd: We observed crayfish this week. We saw how the crayfish live in the water, and eat a plant called elodea, and live in little houses where they like to hide. Some students were brave enough to touch the crayfish's tail while a grown up was holding the crayfish.


Kindergarten: This week's animal is one that are students are familiar with. They've seen them on the school yard, and on sidewalks: the isopod! There are many names for isopods, and most students know them as rolly-polly bugs. As with our other animals, we read about isopods in our animal book, learned about where they live, and about their body parts. Isopods have many body parts that we have heard of before in our other animals. Isopods can live on the land or in the water, but all isopods breathe through gills, just like fish, which is why land isopods need to live somewhere moist. They have legs to help them walk, antennae to help them sense around them, and their bodies are made up of segments, just like earthworms. Isopods also have two small parts on the back end of their bodies called uropods. We will be observing two kinds of land isopods (we saw a picture of a deep sea isopod, which is much bigger, the size of a small cat, and we were very glad that we would not be observing deep sea isopods!). Our first isopod that we observed on Monday is called a sow bug. We drew a diagram of its body, labeled the parts, and colored it in. We saw that sow bugs have flattish bodies, and they cannot roll up.

On Thursday, we observed our second type of isopod, the pill bug. Like sow bugs, they have antennae, legs, and segments. But there are differences between them. Sow bugs had very visible uropods on their hind ends, but pill bugs have their uropods mostly hidden under their rounder shells. Sow bugs were mostly grayish brown without much of a pattern, while pill bugs had a variety of patterns, with spots of yellow and green. The biggest difference is that pill bugs have a much rounder shell, one that allows them to roll up into a ball, which gives them their name "pill" bug. As with our sow bugs, we sketched the two antennae, the seven segments with a pair of legs at each segment, and tiny uropods on the tail. We paid special attention to the color and patterns of our pill bugs when we colored in the diagram. 

Vocabulary: observe, compare, isopod, sow bug, pill bug, antennae, gills, segments, legs, uropods


First Grade: Our wheat seed experiment was ready to be analyzed this week, to help us find out the answer to our question: "What does a seed REALLY need to start growing?" The first step in understanding our results was to see if our control worked as it was expected to. Our control in this experiment was a set of seeds that were given everything we believe seeds need to grow: water, light, air, and space. If those seeds didn't grow, it would mean that something went wrong with our experiment and we would have to start over. But, checking out the seeds in the control cup across all three classes, we could see that they were growing just as expected! That is, most of them were. There were two seeds that hadn't grown at all. This happens sometimes, and it is part of why it is useful during an experiment to set up multiple trials. Since our control worked as expected, we could move on to observing the results for our independent variables, and recording our data. We saw that there were two cups that had no seed growth at all: the cup with no air, and the cup with no water. The cup with no sunlight and the cup with no space both had seeds sprouting in them. The variable cups were set out on four tables, and students were given a worksheet to draw the results from each cup, moving freely around to each station to complete their work. After recording the data, we had to think about what the results of our experiment mean, and what we learned. This is called the "conclusion." We concluded that the answer to our question of what seeds really need to start growing is: Seeds need water and air to start growing. 

Vocabulary: controlled experiment, control, independent variables, conclusion


Second Grade: We have learned that motion is movement, that forces are pushes and pulls, and that motion is caused by forces, sometimes by forces we can't see, like gravity. We learned about rotational motion, and this week, we began learning about a new kind of motion: vibration. Vibration is a quick back-and-forth motion, and vibration causes sound. We observed how vibration causes sound with two hands-on activities. First, each student was given a tongue depressor and shown how to make it vibrate by holding it down on the edge of a table with one hand and plucking it with the thumb of the other hand. We could see the tongue depressor vibrating when plucked, and heard the sounds it made. We observed that we can make the sound change by changing how far off of the table the tongue depressor is positioned. Second, each student was given a plastic cup and a rubber band. The rubber band was placed around the cup, with one side across the mouth of the cup. The students were asked to watch the rubber band vibrate and observe the different sounds made on each side of the cup, top, sides, and bottom. We learned that there are two qualities of sound: volume and pitch. Volume is how loud the sound is. Pitch is harder to explain. We observe that some sounds have a low or deep pitch, and some sounds have a high pitch. We were able to demonstrate the differences with our voices, but understanding what pitch is and why it happens will be part of our lesson for next week. 

Having learned that vibration is quick back and forth motion, and that it causes sound, I demonstrated how to use a tuning fork. When struck, the tuning fork emits a sound, but we cannot see it vibrating. How do we know it is vibrating? Because it is emitting a sound. Is there a way that we could see the forces moving the tuning fork back and forth? Since there are forces pushing and pulling the tuning fork back and forth, we could use those forces to make other things move. We demonstrated this by using a ping pong ball at the end of a string. A student held the string as still as possible so the ball hung almost motionless. The tuning fork was struck and placed against the ball, and the ball began to bounce off of the fork. We also tried placing the tuning fork in a cup water after it was struck, causing the water to spray up the sides of the cup in a burst. Our final thought for the lesson was how sound reaches our ears. Why is it that a tuning fork moving back-and-forth at the end of my arm is something I hear in my ears? This is because of sound waves, which move from the vibrating object through the air until they reach our ears. When they reach our ears and our ear drums, our brain interprets the sound. We saw how sound waves move by pushing air molecules using a metal slinky. One student took an end of the slinky and pulled it away from me, and held it up to their ear. I explained that the slinky was like the air molecules filling the space between the student and me. I struck the tuning fork and touched it to my end of the slinky, releasing some of the coils so that it moved in a wave to the student's ear. 

 

Vocabulary: balance, stable, balance point, counterweight, motion, rotation, force, axis, axle, vibration, volume, pitch

Third Grade: We have learned that adaptation is a structure or behavior that helps an organism survive and reproduce. Last week, we looked at the structures of crayfish, and how those structures functioned to help the crayfish. This week, we examined crayfish behavior. Behavior is action, or what an organism does. Starting with a single crayfish alone in a bin, students observed the crayfish's behavior under various conditions and stimuli. First, we observed the behavior of a crayfish left alone by itself. Then, we reached toward the crayfish, touched its back, its antennae, and its tail. We tried placing it on the table top, then replacing it in its bin and adding a house, observing what happened when the house was first introduced, then what happened after the house had been in the bin for five minutes. Finally, we added another crayfish to the bin.

After observing these various behaviors, students were asked to write about the different ways that crayfish move. We met back on the rug to discuss our observations, and to think about how the behaviors we observed were adaptive. I explained to the students that a range of behavior is normal and can be considered adaptive, the same way that a person can behave in many different ways if approached by a strange dog. For our first observation, some students' crayfish simply sat still in the bin, while other crayfish crawled around the perimeter of the bin. I asked the students how each behavior could be an adaptation of a crayfish living in the wild. The crawling, searching behavior could be adaptive because a crayfish could be crawling around searching for a place to hide from predators. The behavior of staying still can also be adaptive. A crayfish in the wild might be camouflaged against the bottom of its habitat, and staying still might help it go unnoticed by a predator. It also helps them save energy. Of course, it is also possible that staying still is the result of the crayfish being sick. (One group had a particularly lethargic crayfish.) Other behaviors varied by group. Some groups had fairly docile crayfish, while others had very defensive crayfish who spent most of the observation with their pincers raised in warning.

 

Vocabulary: structure, organism, function, seed, seed coat, embryo, cotyledon, germination, adaptation, SWAN, photosynthesis, behavior