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Explaining blockchain to 5th graders

Jawad Sadiq - Nov 25, 2018 · 6 min read

Originally published on – View the original article here.

A couple of months ago, I was invited by Google’s Startup Grind to give an introductory talk about blockchain at the National Incubation Center (NIC) in Islamabad. The goal was to explain what blockchain is (and its implications and use cases) to a diverse audience that included non technical business managers, project managers, digital marketing professionals, advertisers, accountants, programmers and young entrepreneurs incubated at the NIC.

Before this, I had the pleasure of explaining blockchain and its use cases to programmers on multiple occasions including a hands-on workshop at Institute of Space Technology in islamabad. However I was still a little nervous to talk about it in front of a group that would contain people with very little or no technical or programming experience whatsoever. The thing is, when your audience knows some technical concepts, you start with a definition like this:

Then you explain all the keywords highlighted in yellow one by one and then bring them all together to show how each of these play their part to build a Blockchain. But how do you start explaining it to a non-technical audience?

How do you start?

High five if you got the reference but no the idea is not star wars. It’s a story!


Yes. While trying to come up with a simple explanation, I tried explaining blockchain to kids playing cricket in my street, to my mum and her tea party friends from the neighborhood and even to my 7 year old niece. With all the questions they asked and all the metaphors they came up with while trying to repeat what they understood, I came up with the following:

I organized a group story writing activity at a local primary school. There were a total of 23 fifth graders in the class and I allotted each of them a number between 1 to 23 inclusively. Then I asked each of them to take a piece of paper from their notebooks and mark it like this:
Image for post

I told them that as their instructor I have set the following rules of the activity:

1. I will select a number at random (with help of a excel random number generator) and anyone whose number comes up gets to write the next line of the story.

2. After the selected student contributes a line of the story, I would write it down in my spreadsheet. The spreadsheet will also calculate the length of each line (as shown below) and after I am done, everybody is going to copy that line on their papers exactly like it is in the spreadsheet.

Formula for length 1
Formula for length 2


And with these two rules we started playing. After about 12 turns, we had the following story in progress:

This is how my spreadsheet looked like and everyone could see it on the projector display

The paper of one of the students in the class looked like this:

At this point, I asked everyone to turn their papers in and then I disconnected the projector and read them the story we had so far:


Once upon a time, there was a girl who lived near the lake. She was very brave, kind & soft-hearted. Her name Ayesha. One day she out to catch a fish and she forgot to take her fishing rod. On her way back she saw a mermaid, the mermaid was very beautiful. She invited her home for tea. The mermaid said that she cannot walk so Ayesha ran home to get tea.

When I was done, everyone acknowledged the story that I read. So I gave them their papers back, switched the projector back on and asked the next person to contribute the next line of the story. This is how our story continued:

Before the students copied down the next line, immediately one of them raised their hands and said “something has changed”, and just like that all her classmates started questioning what I had displayed on the projector.

Were you, yes you the reader of this post, paying attention like those little kids?

I had changed line no. 9 from “she invited her home for a cup of tea” to “she invited her home for tea”. As excited the kids were to point out what I had done, I was more excited to explain it to them that why I had changed the story.

As I read the story the first time when everyone was without their copies of the story, we were operating in a centralized system. I was the owner of the central server and I could change something that I wanted without anyone really noticing. Later, when I had returned them their copies of the story, and they noticed the difference in numbers in the last 3 lines, we were all working like a blockchain system (I didn’t say ecosystem because that would have been a difficult word for them).

After I was done, I asked the student who was first to point out the change I had made, to tell me what she had understood, and she said:

“When everyone has a copy of a story and they can compare with each other before and after every new line is added to that story, then that story is in a blockchain and no one can change it.”

And so I explained it further, it just doesn’t have to be a story:

    •  Any kind of information that has some kind of value or importance to a group of people, if they put that information in one place, it can be changed or destroyed. But if everyone has a copy which they can compare in real-time, then the information cannot be lost or modified.
    •  Each new piece of information, like each new line of a story, is stored as a block.
    •  Each block contains the information, and some related mathematical calculation; more advanced than the lengths of lines we calculated.
    •  These calculations link blocks to each other like a chain that helps identify, track and avoid changes quickly; like the length of one line is added to lengths of all other previous lines in our example, and changing the words in line no. 9 changed len2 column for all lines below it.
    •  Hence Blockchain in essence is a distributed ledger, that lives inside a computer program. That program not only manages the ledger, but also connects to other computer programs in a decentralized (peer to peer) network and ensures ledger is always in the correct state in sync with all other computers (nodes) on the network.

So what do you think?

In the past couple of months, I’ve run this activity with several groups of people belonging to different age groups, having a variety of professional backgrounds and it has always worked for me.

If you can, please try this in your office, school or community and share feedback in the comments below.

Until then

Written by Jawad Sadiq

Versatile tech professional exploring 4th wave industry disruption. Blockchain, Cloud, & Ruby Aficionado. Founder at Devenings. Twitter: @jay_codez