Tag: STEM

Students often have the misconception that the distance from the sun is the main factor for the change in season. If that were the case, then the Northern and Southern Hemispheres would have the same seasons at the same time of the year, when in fact they are opposite.

Enlighten your students by modeling the movement of the Earth with some simple items. The setup pictured below includes a lamp to model the sun, a globe, a Wireless Light Sensor adhered to the globe with Velcro, and a meter stick to address those pesky misconceptions.

First we can look at the January in the Norther Hemisphere. Students should note the latitude and measure the light intensity using SPARKvue.

Then adhere the Wireless Light Sensor to the Southern Hemisphere at the same latitude as before, but well below the equator to measure the light intensity there.

The “brighter” students in the class will notice that tilt of the Earth has greatly affected the angle of the sensor relative to the lamp. Does the angle of incidence also affect the intensity of the light? The debate may be intense, but let students create a hypothesis before they collect data, then check the data to find out!

With the Earth is at this angle, there is a lot more light coming into the Southern Hemisphere. The amount of light that hits the an area on surface of the Earth is called insolation. The tilt of the Earth affects the solar insolation which is the reason we need insulation for the winter in the norther hemisphere while the Southern Hemisphere experiences summer. For students who assumed the seasons were based on the distance from the sun, this is truly a light bulb moment!

What is happening when the Earth is half-way around its orbit? No need to wait six months, we can fast forward to July simply by moving the globe to the other side of the lamp. Use the meter stick to make sure the globe is equidistant from the “sun” and affix the Wireless Light Sensor to the Northern Hemisphere.

The tit of the Earth hasn’t changed, but now the Northern Hemisphere is pointing more directly toward the lamp. Next we can move the sensor to the southern hemisphere to see if it is still as dazzling as before.

We can illuminate the effect by once again checking the data.

The light intensities have flipped from the previous run as the angle of incidence has changed. Now the Northern Hemisphere basks in the sun, while the Southern Hemisphere needs some insulation due to a lack of insolation.

Using SPARKvue software we can get a year in review by comparing the data.

Throughout this brilliant activity, student should see that the amount of light hitting the Earth’s surface at different parts of the year is based on the tilt of the Earth about its axis, not the distance from the sun. Hopefully, this activity has shed some light on the true reason for the seasons.

When introducing pressure and gas laws, I have always used balloons as a conceptual starting point because they are a familiar item to students. Unfortunately, I could not easily measure the actual pressure inside of the balloon— until now. The Wireless Pressure sensor make this possible and very easy.  Pretty amazing right?  What’s next, life on mars?

Even for those that are absolute beginners to pressure studies, this is a fun experiment, one that’s sure to garner you great fame among your students. Using a slightly larger balloon, and a little patience, the students who are able to get the pressure sensor into the balloon will definitely be heroes (if just for one day)

Now, with the sensor secured inside the balloon, let’s dance— or at least begin the experiment. Turn the sensor on and connect it to your device so your students can commence a countdown and start collecting data while they inflate the balloon!

The analysis tools in SPARKvue, allow the students to observe the pressure ch-ch-changes over time.

Some things to initially note could be the slight increase in pressure as the balloon is inflated, the changes in pressure as the balloon is compressed and the sharp decrease in pressure as when the balloon is popped. It’s a fantastic voyage through the many phases of the pressure change.  Seeing data displayed in real time helps connect the science behind the sound and vision of a balloon popping.

Now that they have been engaged by the activities and explored the data (and before they start to act like a rebel, rebel) try having the students explain and elaborate on what is happening and why.

With this activity only taking a few minutes to complete it can be used as a demo, as a quick investigation or it can be grouped with a few other basic investigations where students move station to station to learn about gases. And as students begin to construct their knowledge about gas properties using familiar items, you can incorporate the empirical gas laws leading up to the ideal gas law.

To make this a truly memorable lesson, you and your students should be listening to “Under Pressure” by Queen and David Bowie while performing the activity.   All the young dudes (and dudettes) will enjoy this one.

Phase changes are an important part of chemistry and physical science curriculum — and Freeze Pops are an important part of everyone’s summer. What better way to take the edge off the summer heat than combining the two to make a cool activity that addresses changing states of matter?

In the science lab, temperature measurements will help crystalize students’ thoughts around freezing and connect the phase change with particle motion.

To set up this cool experiment, you’ll need to get a base line temperature change of pure water as well as the temperature change of the Freeze Pop. First, pour some water into a plastic container and add a Wireless Temperature Sensor. Next, we’ll open two Freeze Pops (that haven’t been frozen), pour the contents into another plastic container and add a second Wireless Temperature Sensor. Now you can use SPARKvue’s remote logging capabilities and put everything in the freezer. And if you really want to sweeten the inquiry, add some additional Freeze Pops as a tasty post-experiment treat!

The Wireless Temperature Sensor can remotely log data for days, but we’ll only needed a few hours. After letting the samples set overnight, it was time to check the results.

The samples look frozen. Let’s check SPARKvue to see if the data is just as solid.

I started by checking out the water. No brain freeze here— that’s just cool data.

The students will notice that the temperature dropped to 0^oC, and stayed there before dropping again to the temperature of the freezer. But what’s so special about 0^oC and why the plateau?

The students may know that this is the freezing point of water. But they may not realize that the water sample can’t get below the freezing point until the entire sample is frozen. This is where particle illustrations become important.

As the water molecules cool, they slow down into a regularly repeating pattern forming a solid. But why the plateau? As long as there are some faster, freely-moving water molecules in the sample, there will be an equilibrium between the liquid water and the ice keeping the temperature constant. Once all of the water molecules are moving slow enough to be frozen and in the solid state, then the temperature can begin to drop again.

Is the same thing happening with the Freeze Pop? It’s a good thing we have hours worth of data to find out!

This sample, which is not pure water, froze at a temperature that is lower than zero. The freezing point is depressed— but you shouldn’t be. This always happens with a solution. The other particles in the sample (sugar and dyes mostly) get in the way of the solid-liquid water equilibrium and lower the Freeze Pop freezing point.

Students may also note that there is not a flat plateau during freezing. As the water freezes out, the sample gets more concentrated with the “other” particles, depressing the freezing point even more. The freezing slope isn’t steep enough for sledding, but it is definitely noticeable. Once the entire sample is frozen, the temperature decrease is more dramatic.

The concept of freezing point depression is important and it has real practical applications— from making Freeze Pops and ice cream, to car antifreeze and melting ice in the winter.

Now your students can not only understand freezing, but they can explore factors that would affect freezing point depression. I am sure this would open up the lab to 31 flavors of ice cream inquiry!