# Half Hour of Code, Montessori Style: Check Out This Free Binary Counter

When I approached my four-year old’s teacher about Hour of Code, she invited me into the classroom to do a half hour lesson. My little ballerina goes to a Montessori, so the classroom is computer free.

“How hard can it be,” I thought. “I will just grab something off the internet and teach from that.”

So I told the teacher that I would be happy to do this.

I discovered how hard it is to plan a lesson for four-year-olds, both when following a lesson plan and making a new one.

After giving a successful lesson on counting in binary and the Divide and Conquer algorithm, I have a new found respect for preschool teachers.

I talked with my daughter’s teacher to get time and content guidelines. She advised me to keep the presentation to half an hour for the age group, to spend half the time talking and the other half with an activity. Additionally, she thought I should bring in both activities when I talked to her about the two ideas I was thinking about.

Okay, great, so I can talk about how computers think in ones and zeros and counting in binary for 7 minutes and 30 seconds, then have the kids count in binary for 7 minutes and 30 seconds. After that, I could talk about algorithms and the divide and conquer algorithm for 7 minutes and 30 seconds, followed by the kids doing divide by zero for 7 minutes and 30 seconds. Plus, I get to do this in a way four-year-olds will understand, and without anyu computer.

Um, yeah, that sounds easy … or not.

Time to get organized. I tackled the Binary work first, and then the Divide and Conquer work. I had the requirements from Samantha’s teacher. Now to put together the lesson plan.

The lesson plan consisted of the following four elements:
Read A Robot Story, Learn to Count in Binary by Lisa Seacat DeLuca.
Work with a binary counter I created.
Read Santa’s Dirty Socks, a divide and conquer story from csunplugged.org
Use the school’s balance scale to divide and conquer a present missing some of its parts.

If you would like to use the lesson plan without (some of) the work I put in, here is how it came together:

I have a signed copy of A Robot Story from Lisa’s Kickstarter. I read the book to my daughter often, so I know the book well.

Check, I had the first 7 minutes and 30 seconds covered quickly.

I searched the internet for something to help the children visualize how binary counting worked. I found one option that included cards for ages 7 and up. These cards with counting gave me the idea of the binary counter. My daughter loves doing works where she counts the shapes, and then writes down the number. But loose cards and going up to 31 would be too much for her.

With that in mind, I created the binary counter. Given I was reading a story about robots beforehand, I decided to have robots for the counting items. After several different tries, I came up with a counter made from a single piece of paper.

On one side, the ones and robots are printed.

On the other side, the zeros as well as instructions and a place for kids to write their names.

When folded in half on the dotted line, the zeros lay on top of the ones.

Cut on the black line to allow the zeros to turn up, and the ones and robots to show.

At this point, the child can count the numbers, and figure out that 1010 has 10 robots, so 1010 is binary for 10. The counter goes from 0 to 15.

To make the counters their own, I made them coloring sheets, and gave a space for them to write their names.

I tested it out with my daughter, and she quickly caught onto the concept as I worked with her.

All right, the first 15 minutes are planned. Now time to work on the second 15 minutes.

I choose Divide and Conquer because csunplugged.org has a wonderful book and lesson plan for it, plus it uses a balance scale, which the school already had. I figured this would be the easy 15 minutes for me to plan. (More on doing a balance scale if you don’t have one at the end of the article.)

I figured wrong….

The first part of the book is Santa’s Dirty Socks. The title alone is sure to get four-year-olds excited.

Just one little problem. The book came in pdf format, I had no color printer, and Kinko’s wanted over \$30 to get me a print of the book. I asked the school to print out the book for me.

I learned one thing from this, always test a page or two before printing everything out. The problems that came up are:

The book was designed for landscape but printed by default in portrait.

The book used a font that the school did not have. This caused it to print out the text uneven.

Any word that started with a “ti” or “fi” printed as a square. I added the missing letters, then put everything in a binder to read from.

After this, I practiced reading the book a few times and moved on to the activity. Here the children would take 32 items that looked the same, and figure out which item was different by weighing half at a time. The school had a scale.

I just needed 32 really small items, one of which looked the same but weighed differently. After many hours of searching and racking my brain, I came up with tiny presents wrapped in ribbon. My daughter loves the “jewels” and jingle bells she gets at school, so I made each present out of two jewels and two jingle bells.

Then, I created one gift with just the two lightweight jingle bells and left the two heavier jewels out. I used a piece of bubble wrap in the middle to give this package the same look at the other packages. Then I marked it with extra clear tape, so I knew which package was the light weight package.

Thinking over it, I decided the children would like to keep a present at the end, and they would be more motivated to find the present if they knew what was in the packages, and what had been left out. So I made 32 complete packages, 31 for the activity and one to open beforehand. Then I made one light package and brought two extra jewels to show the kids what have been left out.

Then came the moment of truth for my little packages. As you can see from the jewels, they were not uniform in size. Would the scale show the lighter side?

When I weighed the heavier packages one at a time, they all came out looking balance. Okay, good first step.

I found the best way to weight the presents is to divide the pile in half by counting, then put one pile in one bucket, then the other pile in the other bucket. This was quicker, and it was easier to see what was happening.

The needle of the scale did not point straight up, given the use it had gotten. So I tried the light piece on one side, and it was not obvious which side was lighter.

When I did the other side, however, the scale showed which was heavier. So I needed to make sure the marked package got into the right bucket to show the difference.

From there, I checked the packages going to one. After the first divide, the scale showed the side without a problem.

My lesson complete, I packed up and went to my daughter’s school. I walked into the classroom, and my daughter saw me. She ran towards me, yelling her name. The next thing I knew, all her classmates came around me. They asked me about computer science. Then, they went to their circle, sitting down to wait for me to talk.

I asked the children if they ever used a computer, tablet, or phone, showing them my turned-off phone as a reference. Almost all of them had.

I asked them how they got what they wanted on the phone. The pushed the images and buttons to get what they want.

I shared that my work made the buttons and programs that appeared on the phone. One little boy then asked if I was a “computer construction worker, making the things in the computer.” That is by far the cutest title I have ever had.

I talked about how computers only think in ones and zeros, and that we would be learning to count in ones and zeros today. The kids got excited about the book A Robot Story. It turns out that my daughter has shared the book with them before.

It seems I am raising a geek.

I got to the binary counters, and this is where I messed up. I handed each child a counter before explaining how to use it. The kids started looking at the counters each had, and only got the edges of how to work them before we moved on. It was something, but not as much as it could have been. The children would get the idea with one on one lessons.

My advice on how to change this step. Either introduce the counter one on one; or talk the children through using it, including counting to figure out a few binary numbers, before giving each child their own counter.

Still, the children were excited about the counters, and several figured out that 1111 is 15 in binary.

As soon as I told them the name of our next book, Santa’s Dirty Socks, the children got excited. They enjoyed the story, even if they did not understand what it was doing.

Time to put something tangible to what they had just read. I pulled out the presents, told them I had a present for each of them. I opened up one of them, passed it around so the children could see what it contained.

Then I told them our problem, holding up two jewels. I had forgotten to put these jewels in one of the packages. Did they want to help me find the package, so each child got a complete package.

They did.

They agreed that the missing package would be lighter, and so would be on the scale side that went up.

I asked them if they knew what half of thirty-two was. Being four, they did not. So we counted them out, putting them in two piles of sixteen.

I pulled out the scale. I put half on one side, and half on the other. I asked them which side had the bad package. Half the kids pointed to each side. I directed them to the high side.

We counted out, this time to eight, and weighted again. This time, several of the kids knew which one had the light package.

We counted out to four. The kids had gotten it. They found the light side on their own. They were excited when we went to two packages on each side.

When we got to one, the kids all pointed and said, “that is the empty present.” We opened up the present and the kids saws they were right. Better yet, they each now got a present of their own, which they knew was in a good state.

Afterward, the classroom teacher said she thought she might continue working with the ideas. She liked how tangible the lesson was, and how you didn’t need to know computer science to teach it. She really liked that divide and conquer used tools and concepts similar to what she already taught in class for the natural world.

That night, I asked my daughter how it was having me in class, she said everyone thought it was fun. She asked if we could read A Robot Story, and use it to help her with her binary counter. A Robot Story counts up to ten.

My daughter informed me that the counter went up to fifteen. Could I please make her a book that went up to fifteen? I told her I would work on something for her.

If you are interested in what I come up with to satisfy my daughter’s desire for a binary zero to fifteen guide, comment below. If there is interest, I will share it when I am done.

If you are interested in doing this lesson at home, please use the resources below. It includes where to get the books, divide and conquer lesson plan, and binary counter download. Additionally, it includes links to either buy or make a balance scale.

## 3 thoughts on “Half Hour of Code, Montessori Style: Check Out This Free Binary Counter”

1. Value says:

Wow, I wish I could’ve had computer science taught to me this way. Much respect for your well-considered lesson-plan and thoughtful description of how it went. I love all the tangible things. As a kinesthetic learner, I think the abstract ideas of code and computer science can be frustrating and intimidating. This seems like a great way to introduce kids to the concepts with things they can touch, do, hear, and see.

2. ontiptoe says:

I love this idea and can’t wait to try it with my girls. I’d love to see what you come up with for the binary zero to 15. Now off to see how many things I can still get shipped in time for Christmas. 🙂

3. Claire says:

Thank you both for your kind comments. I will continue to share what I come up with in this area.