Coding Unplugged – A number sorting computer

I learned an amazing coding activity at the #NCSTA17 conference in Greensboro, NC in October. The activity is from The mat works like a computer. It has rules and paths the information must follow. I was mind blown the first time we did it as adults at the conference and I immediately had the idea to use this as one of my comparing numbers introductions. #math1NBT3

The first time I did this, I taped the pattern out on the floor copying it from the photo I took at the conference. I didn’t want to spend the money making the cloth if it didn’t work. I was worried that my firsties wouldn’t get it since they would need to know right from left in order for the computer to be successful. I was so surprised! They did not want the computer to “break” and were very careful to chose the correct direction and help each other figure out where to go on the coding mat.

I bought this drop cloth at Lowes. I painted the pattern with tempra paint from my classroom. I copied it from the photo I took at the conference. It was pretty easy except I didn’t eyeball the paths correctly and ended up with 2 curved ones when they should all be straight. I also had a few cat prints from my dear sweet 15 year old torti cat, Calypso, being nosy and walking across the mat.

The kids DID NOT MIND! They love hearing all the crazy stories about my pets!

The first time we did this, I gave the kids single digit numbers 1-6 that I knew they would be able to compare and put in order easily. I had them line up out of order at the starting end of the mat. I asked the kids who were not on the computer to tell me what they noticed:

  • “They are 1 digit numbers.”
  • “They are out of order.”

So far so good! I explained the rules and paths on the computer and gave reminders for right and left so the knew which direction to move. At each step forward I had them stop and the observers to notice any changes (Nothing changed except the order of the numbers. And they were still out of order.) I slowed this WAY down. One step at a time asking them to compare and decide: right or left? By the time they go to the other end of the computer they were just as amazed as I was at the conference that this unplugged computer WORKED!!!

The next time we did this, I gave them teen numbers which I knew they were familiar with from kindergarten and had 1 or 2 numbers missing (i.e. 11, 13, 16, 17, 18 19). I kept it at a slow pace. Taking 1 step at a time and comparing and following paths and asking the observers to notice any changes. They were less surprised that the numbers ended up in order and more concerned that some numbers were missing in the order. This led to a great conversation about comparing numbers and the numbers that come between other numbers.

We moved on from there comparing more 2 digit numbers. I gave out another set of cards with 2 digit numbers specifically chosen so that it didn’t matter if they only compared 1 of the digits, it would still work out in order (i.e. 12, 23, 34, 45, 67, 89). I anticipated this would be a common misconception with comparing 2 digit numbers. We talked about always comparing with the tens number firs then the ones if the tens were equal.

The next set of cards had more random 2 digit numbers. I had them draw the base ten picture for this number so they could begin comparing both the number and a picture of that number and visualizing each 2 digit number. The last set of cards had just base ten pictures and they compared the images.

Each time I gave out a new set of cards, I called different students to be in the computer so that everyone could have a chance to observe and notice and participate. Each time we worked the computer, they were able to follow the rules and paths faster. Our observation skills even got keener as they noticed mistakes in the right/left stepping and corrected their friends so we didn’t “break” the computer.

Please share other unplugged computer science or coding activities or ideas you have for this activity in the comments!

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