Learning Festivals in Missouri

This past week on the road was a bit unusual: in the past five days, we spent only one day riding, and four days teaching.
Our first stop was in Farmington, MO, just an hour out of St. Louis. We taught at Lab:Revo, a community maker-space in the basement of a factory founded four years ago by Ann Boes. The maker-space was entirely run by volunteers in the community and offers various robotics, Arduino, 3-D printing, and other engineering activities for kids of all ages in the area. This setting was far more informal than the Challenger Learning Center in KY, and we taught a smaller group of local kids who were Lab:Revo regulars.
Our next stop at the St. Louis Homeschool network had a similar feel to Farmington. We taught in the United Methodist Church which the network often used for classes. In the 18 hours of teaching over the past five days, we all had a chance to ramp up our workshops.
In Masha and I’s circuit workshop, we had the opportunity to collaboratively build a 5-bit binary adder (Translation: a calculator that can add two numbers up to 31).
For those of you who haven’t dabbled in circuits or computer architecture, here’s a run down of what we do in our workshop.
We start by warming up with a small circuit that turns on an LED (translation: light) and then a static electricity detector that teaches the students about transistors, the basic semiconductor building block of a computer.
We then learn binary, the computer number system which only uses two digits: 1 and 0.
After learning about three basic logic gates, the students build a half adder on their circuit boards. A half adder is a combination of logic gates which can do a 1-column addition problem. This “machine” takes in two 1-digit numbers to add (each 0 or a 1) and then a carry (just like the carry you might have when you are adding 2 numbers by hand). It then outputs a the sum bit of those numbers and the carry to send on to the next column of the addition problem.
The students then cascade their projects together to create an adder (calculator) that can add longer numbers. We were able to build a 5-bit adder today that could add two numbers up to 31! The answer is displayed in binary on lights – “ON” means 1, and “OFF” means 0.
Its always fun seeing the circuit calculator get the right answer at the end, and it’s a good example of modularity in computers – how simpler units fit together to form a larger, more complex unit.
-Margalit
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