By: Dave DeWitt, Editor
This summer Manchester Community College in New Hampshire offered a series of STEM Manufacturing Camps for 5th – 8th grade students through their Workforce Development Center. This is the fifth year hosting these camps through the Fabricators and Manufacturing Association; Nuts Bolts & Thingamajigs grant program. The camps focused on exploring engineering, manufacturing, design, and robotics though hands-on learning in the Advanced Manufacturing and Robotics lab at MCC. Each of the five camps had a different focus and series of learning activities. In addition to the activities and learning, students are introduced each day to a different guest presenter who talks and presents different career pathways for students. Each presenter brings a unique perspective to manufacturing and engineering showing and explaining what they do and how to explore career pathways in manufacturing.
Frank Xydias, M.Ed., organizes the summer STEM programs at MCC. Frank is also the head of the Pre-Engineering Department at Milford, NH CTE center which is where I first met Frank. For the last 3 years, Frank has been developing a STEM outreach program at Milford HS. This program invites middle school and elementary school students and their parents to attend “awareness” nights at the CTE center. While the parents hear presentations from the CTE staff and visiting local business partners, like myself, the students participate in short projects that have been prepared by the high school students. This is a great learning and mentoring opportunity for all! We recently published a wonderful story about Frank’s “NEW STEM” pathway program. Since I knew Frank organized the summer STEM camps at MCC I mentioned I’d be glad to help out this summer. Frank is really wonderful about involving his industry and educational partners in his programming.
The rest of this post outlines my “Fun with littleBits and Physics” project.
This project uses a number of littleBits modules to control two DC motors set up in a winch configuration. The winch pulls a “sled” (a plastic draw from shop storage draw set). The students can add weights (some big washers) and observe the effect on the speed of the sled. The wooden base is a 24″ x 8″ shelf from a bookcase in my office. The white plastic material has rubber on the back and was made from some material I had purchased many years ago to make “mouse pads” (some of you may be old enough know what those are ????). I drew some lines spaced one inch apart on the plastic and numbered the lines 1-10.
My goal with this project was to introduce the students to some basic Electrical, Mechanical and Energy concepts. I placed supporting documents of the whole project in a DROPBOX FOLDER for others to use. To better understand the rest of this presentation you may want to download and print out the Circuit Diagram. The purple text identifies the littleBits modules by their official product numbers in the littleBits online store. All littleBits have three conductor plugs to connect them together. (Positive, Negative and Control – best to refer to the littleBits website page, ABOUT the BITS , for a more detailed explanation of how the bits work and connect to each other)
The image to the right is a close up of the littleBits set up. Everything is run off of a 12 volt battery. Since littleBits themselves operate on 5VDC the students learned that the Powerbit also incorporates a voltage convertor/regulator to reduce the voltage to 5 volts. I then added a series of single pole switches and talked about how since all of the switches are in “series” all of the switches have to be ON for the first “flex LED” to light. Then by pressing the push-button the power is transferred to a slide (variable) resistor. With the slider set to (0 resistance) the full voltage of 5 volts is sent to a 3 way Circuit Fork (Splitter). Two of the branches are connected directly to the two DC motor modules. In order for the winch to work correctly one motor must run clockwise while the other runs counter clockwise. Each of the motor “bits” include a small reversing switch and we talked about how DC motors can be reversed by reversing the polarity to the motor. The third branch of the circuit fork is connected to a LCD seven segment digital display set to display the voltage. With the variable resistor set at 0 ohms the voltage was 5 VDC.
Of course along the way we talked about voltage and current and a bit about how LED’s actually work (see inset on the TERMS USED PAGE in the dropbox folder). From the seven segment display the circuit continues to a Pulse Generator Bit that powers an RGB LED and a Buzzer. This is where we covered machine SAFETY. When you press the push-button the motors run, the winch turns, the sled moves and the RGB LED flashes ORANGE while the BUZZER sounds intermittently. We talked about how engineers always must think of SAFETY FIRST in all of their designs.
We then generally discussed the factors involved with friction. Those being the vertical downward force of the sled, the type of surfaces that are sliding on each other (coefficient of friction) and the surface area. Finally, we talked about the conservation of energy. How the chemical energy in the battery is converted to electrical energy and then all the places where that energy was used up in the form of light, sound, and heat. We just spoke about things in generalities and as I introduced each general topic I asked the students for examples that they could think of from their experiences. There were plenty of good STEM ideas discussed in their own terms.
This concluded the first half hour of the project presentation. I had prepared two project set ups so we broke into two groups of students and they were told they could just experiment on their own and have FUN! What happened next was quite amazing … I purposefully had never mentioned to the students anything about the 10 lines on the white plastic sheet. One group decided to run some experiments. They used the stopwatch function on one of their phones to time how long it took the sled to move between lines depending on the amount of weight they put in the sled. I told them Observation is how folks like Newton and Marie Curie learned about physics. Meanwhile the second group was doing something similar by varying the voltage to the motors while keeping the weight constant.
Then the most wonderful thing happened. When I returned to the first group they decided to see how the surface area would effect the speed of the cart. In all of the times I have run this project with students and adults I had never really figured out an easy method to accomplish this learning objective. The answer was unbelievably simple! The students just turned the cart (drawer) over so only the thin drawer sides were in contact with the plastic sheet! ???? When I returned to the second group they discovered that by turning the plastic sheet over so the cart was sliding on the rubbery side that really slowed things down to almost a stall of the motors. “It must be that rubber has a higher coefficient of friction than plastic,” one student exclaimed with a smile!
Frank and I hope you enjoyed this project and please feel free to use the resources we have provided.
If you would like to learn more about the NBT programs at MCC please contact Frank Xydias
If you would like to learn more about building or running this project you can contact me directly via our website CONTACT FORM.
Finally I hope you will sign up for our great weekly STEM Newsletter.
About the Author:
I’ve been involved with manufacturing from an early age as my dad ran a manufacturing plant for a large toy company. My key interests are manufacturing, business and STEM education.
My business background includes manufacturing corporate and private – retail shipping services – online media.
My education background includes K12 STEM program awareness, development and sponsorship, promoting collaborations and partnerships between industry & education, NH state education committees and local maker activities
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