BeeSpi v in the Physics Classroom

In the lab, however, I noticed a persistent disconnect. With the exception of displacement and time, our hands-on investigations rarely mirrored this problem-solving process. We didn’t have an easy, reliable way to directly measure a non-zero instantaneous velocity or acceleration in real time.

Determining instantaneous velocity isn’t always intuitive for students. If I see a ball rolling across the floor, I can measure out a known distance, time how long it takes to travel that distance, and divide to find velocity. Whether the tools are a meter stick and stopwatch or a sophisticated photogate system, the result is the same: we calculate an average velocity between two locations.

This method is blind to what happens between those points. If the object moves at constant velocity, that’s fine—the average velocity equals the instantaneous velocity everywhere. But if the object is accelerating, the velocity is continuously changing, and the average velocity only matches the instantaneous velocity at a single point halfway between the start and end positions.

This is where BeeSpi changes the game.

The BeeSpi v Probe

The BeeSpi photogate measures the instantaneous velocity of an object as it passes through the probe. Inside the housing are two infrared light beams separated by a known distance. As an object passes through, it breaks the first beam, starts the timer, then breaks the second beam, stopping the timer. Using this distance and time, BeeSpi calculates and displays the velocity.

Because the measurement occurs over a very small distance, the value represents the instantaneous velocity of the front edge of the object at the midpoint of the probe. Since it’s a dual photogate, the object’s overall dimensions don’t matter - only the leading edge needs to break the beams.

The opening is large enough for marbles or Hot Wheels cars to pass through directly. For larger objects, a simple “flag” can be attached to extend into the photogate gap. Arbor Scientific even offers ready-made setups using Hot Wheels track systems, such as the Introductory Energy and Motion Lab kit.

The best part? The setup is fast, the data collection is instant, and the probe resets immediately for the next trial.

In our classroom, we use 2020 aluminum extrusion rails as constant-acceleration marble ramps, along with 3D-printed brackets to mount the BeeSpi probes directly to the rails. A detailed set up configuration with links and files can be found at https://passionatelycurioussci.weebly.com/beespi-marble-ramp.html 

Using the Probes in the Classroom

When we added a classroom set of BeeSpi v probes, it truly transformed our experimental investigations of motion. For the first time, students could directly measure instantaneous velocity with minimal setup and high precision. The following are some examples of how we have used the probes in our classroom.

1. Exploring a Squared Relationship

We like to begin the year by examining different mathematical models and strategies for linearization. As a quick physical example of a square-root relationship, students roll a marble down a ramp starting from rest and plot displacement (x-axis) versus final velocity (y-axis). The clarity of the data makes the underlying relationship immediately visible.

2. Kinematics in Action

One of my favorite kinematics practicals involves rolling a marble down an aluminum ramp and using two BeeSpi probes to measure the initial velocity, final velocity, and displacement between them. With two probes per group, all the data is collected in a single run that takes just a few seconds.

Once the data is collected, I confiscate the marbles and students calculate the acceleration of the marble on their ramp. To test their result, I assign a random location along the ramp and ask them to predict the marble’s final velocity at that point.

When they’re ready, they call me over. I place a BeeSpi probe at the target location, return the marble, and we run the test. I’ve used this as a practical assessment, grading students based on how closely their predicted velocity matches the measured value.

What’s remarkable is the precision—students are often within 0.03 m/s of the measured result, a level of agreement that is rarely seen in a high school physics lab.

3. Horizontal Projectile Velocity

Another standout lab is the horizontal projectile prediction challenge. Students calculate where a marble will land on the floor after rolling off a table, given the launch height and initial horizontal velocity. To make it memorable, we use carbon paper and a target featuring my face with point ranges printed on it. 

Historically, the biggest source of error in this lab was measuring the launch velocity accurately. Once we introduced BeeSpi probes, that problem disappeared.

Now, before I even explain the final challenge, groups use the BeeSpi to measure the marble’s velocity until they achieve three consecutive readings within 0.01 m/s. Once they are able to demonstrate consistency, I confiscate their marbles and reveal the challenge. They must tape the target to the floor to maximize their score without another test launch to guess and check.

For fairness (and drama), the target is covered with carbon paper so the marble leaves a visible mark on impact. The suspense during the final reveal never gets old.

5. More Possibilities

As with any new equipment, we are still exploring new ways that we can incorporate these BeeSpi probes into our physics courses. Here are just a couple of other ways that I have heard people have used these for

• Investigations to determine the acceleration of free fall
  
• Explorations of energy conservation using the probes to measure and calculate kinetic energy
  
• Using the lap timer feature to time the period of a pendulum

Setup Recommendations

For classroom use, we found that two BeeSpi v probes per lab station made initial and final velocity measurements especially clear. That said, because data collection is so fast, it’s also possible to use a single probe with multiple trials if the motion is repeatable.

Be sure to order enough batteries—each probe requires two AAA batteries.

You’ll also need a track system to keep objects moving in a straight line so they reliably pass through the photogate. This could be a Hot Wheels track, aluminum rail, or even grooved tracks designed for Vernier or PASCO carts (a marble fits nicely in many of these).

Finally, you’ll need a way to hold the BeeSpi in position. A 3D-printed bracket works well, but depending on the setup, the probe can also sit on the table or be taped in place if the alignment is right. The options posted here https://passionatelycurioussci.weebly.com/beespi-marble-ramp.html could provide some inspiration if you are looking to assemble your own solution

Bottom line: BeeSpi doesn’t just measure velocity—it bridges the gap between kinematics on paper and motion in the real world. For students, that connection is everything.