Sphero is a ball shaped robot that can helps teachers teach basic math and science concepts. The robot can be programmed to travel across a surface with a single line of code. With this single line of code, students can learn a variety of science and math concepts. In science, we can teach velocity, acceleration, and force. Students can take measurements in U.S. Standard or in the Metric system. Students can also learn to use formulas to solve problems. This is a lesson taken from my book "Sphero: Coding for STEM".
Velocity is the measure of how fast something is going in terms of distance per time. Velocity is measured in terms of miles per hour or feet per second when talking about Sphero. To calculate the velocity of Sphero we need to know two things. We need to know the time and the distance. We know the time because that has been configured in the code parameter.
The distance needs to be measured. This can be done with a yard stick or measuring tape. It can also be done with string. Students can mark the start and end points of the string. They can then take that string to a meter sick or yard stick that is placed on the wall or other surface. Teachers can help students take the measurement from the string. This can be much easier than trying to measure with rulers and yardsticks if measuring tapes are not available.
Let’s look at an example. To keep things simple let’s say that Sphero travels 6 feet in 3 seconds. In the formula for velocity, we divide distance by time. Divide the distance 6 feet by 3 seconds to get 2 feet per second. This provides a teachable opportunity to discover how velocity changes with the amount of energy provided to Sphero. Change the Speed variable and measure the distance.
Teachers can create an activity where students get into groups of three. Each group will measure the velocity of their Sphero at different energy levels. Each group can measure the velocity for three different energy levels. In a class with five groups, Acceleration is part of velocity, we can get 15 measurements. We can divide the fifteen measurements across the 255 energy levels. This means that students will measure the velocity at intervals of 17. Students can record their results in a shared spreadsheet. This table can give students a good indicator of what the different energy levels translate to when they are applied in a Roll parameter.
Using the slider to set the energy level can be challenging. Tap on the number to the left of the meter. This will open a keypad where we can enter a specific energy value.
Acceleration is part of velocity because velocity is a change in motion with direction. Sphero needs to accelerate from a point of no acceleration. To measure acceleration, we need to know the velocity and the time. We know both of these from our math we did before, and from the parameter, we provided in the block of code. Acceleration will be used to help determine the force applied.
Acceleration is the difference between the initial velocity and the final velocity. This is divided by the initial time and the final time of the acceleration. The initial velocity in our example was zero and the final velocity was calculated at 2 feet per second. The initial time was zero and the final time was 3 seconds.
We subtract zero from 2 and zero from 3. I like simple math. Now we divide 2 by 3 and get .67 feet per second. Sphero was accelerating at .67 feet per second for each of the 3 seconds it was traveling to reach a maximum of 2 feet per second. This is only an average. Sphero might have reached the final velocity in the first second and maintained the speed for the remainder of the time. This is a good time to discuss averages, and how it applies to the calculation of acceleration for Sphero.
In this lesson we subtracted, divided, used decimals, used intervals, and talked about averages. That was a pretty good math moment.
Force is the amount of work done. Force is measured in Newtons. To calculate the force of an object we need to know the mass and its acceleration. We just calculated the acceleration. We need to determine Sphero’s mass. To determine mass we need either a balance beam or a spring scale. Measuring the mass of my Sphero it comes to just over 100 grams. We’ll round this to 100 grams to keep the math simple. We need to multiply Sphero’s mass, 100 grams, by the acceleration, .67 feet per second, which we calculated earlier. This gives us a force of 67 Newtons.
We can include the multiplication of decimals to our list of math accomplishments for this lesson. Awesome!