Let’s sort some coins…


Our first design challenge of the year. This one was for my more seasoned group of makers. I planned to introduce the concept of Engineering Design Process, a one of a kind in any international schools in India. What made it more exciting, was the fact that the design once completed, could potentially do something. An outcome that involves action is not just thrilling to watch, but to work towards as well.

I had a couple of reasons for bringing this challenge into class,

  • First, I was hoping to introduce the Engineering Design Process to my students, through this activity. I wanted them to understand that the final product is important, but equally, if not more important is the process that leads one to that design! This process needs to involve a set of somewhat structured thinking and working steps.  Not only did I want them to relate to these different steps, but to also apply them in every one of their design tasks, going forward. It is true, that too rigid a design method might take the fun and creativity out of the process, at the same time, a completely haphazard approach to design could lead to wasted time, materials, effort, and not to mention, probably an unsuccessful solution. I was wishing that with enough practice, my students would be able to hit middle ground, and use the EDP to churn out one successful design after another.
  • Second, I wanted to drive home the point that every design starts with a real life need with a real problem. When students are able to see this connection, there are two things that begins to happen. First, they are filled with a sense of satisfaction over having solved something that is real, which fuels their urge to do more of it in future. But more importantly, they start looking at problems around them not just as problems, but instead as opportunities to come up with a solution. And that to me, is a very big shift in thinking and perspective, that has the potential to shape students into observant, empathetic, responsible, and motivated problem solvers!

We started off with some theory. We talked about how in the past, whenever a new challenge or design task was introduced in classes, there would be a lot of questions. Questions on the design and what it needed to do, on the materials and how much of it would be available for making, on the amount of time to complete the task, and of course on the all important matter of student grouping. On getting answers to these questions, students would start their work. Work that involved ideating, discussing, deciding, building, testing, and fixing. Sometimes, the students ended up with a design that they were satisfied with, sometimes they realised they had underestimated the challenge, or over thought the design, or fallen short on materials, or run out of time, or had entirely messed up and needed to start over again. All of which, is completely fine, and as a matter of fact, it is part of the learning process. But that shouldn’t stop us from aspiring to work more smartly, or design more effectively. And that’s exactly where the structure lent by the Engineering Design Process comes to the rescue.


We discussed the various steps involved in the process, and came to a mutual agreement on the following :

  1. Even without knowing about the existence of the EDP, in the past, we had somewhat naturally flowed through a design process. The steps might not have been in the same order, and some steps might have even been non-existent.
  2. We repeatedly fell short in the sketching department. Even though, every single challenge in the past had worksheets to sketch out our ideas, our drawings often lacked in detail, scale, the way it is presented, and not to mention, the purpose.
  3. In our hurry to start creating, planning was always forgotten. We didn’t worry about timelines, or work sequencing, or material planning, or division of effort, all leading to design confusion, and sometimes incomplete outcomes.
  4. Documenting our work, and sharing our designs had not been given their due importance. Despite realising the value of learning from each other’s experiences, and moving forward as a group, sharing had many times been sacrificed in favour of more design time. 🙁

After agreeing to take our sketching, planning and sharing more seriously, we moved on to our actual challenge.

Our challenge started with a story.

…A group of boys, over the summer break, decided to set up a lemonade stall in their neighbourhood. With the summer being a particularly sweltering one, their chilled drink became the talk of the area! As business boomed, so did their cash flow. By the end of summer, they ended up with a bucketful of change. Sorting through the change by hand would have been a laborious task. The boys neither wanted to spend the time, nor did they want any man-made errors. Additionally they were way too cool and popular now to do it by hand. They wanted a machine to do it for them….

Here was our “real life problem”, our chance to meet a “real need”, and come up with a “real solution”. And we were going to do just that.

Design a coin sorter that could segregate change into Rs. 10, Rs. 2, and Re. 1 coins, and collect them in separate containers.

Before starting the challenge, even before forming teams, I had my students “ASK” their questions on the task. Most queries were on materials, deadline, and groups. But there were a couple of technical questions as well, on how many coins the sorter needed to handle at a time, and whether electronic sensors were required to solve the problem. Students soon started “IMAGIN”ing, drawing and writing down their individual ideas, following which I let them team up in fours. Being the first challenge of the year, I chose to let them pick their comfort groups. Once in their groups, they exchanged ideas, brainstormed, weighed out options, and got cracking on their design sketches. For the first time, I decided to leave the material choice wide open. Instead of handing over a preset bunch of materials to each team, I allowed them to think about how they wanted their design to look and work, to visualise different materials, and to consider each one’s sturdiness, flexibility and ease of use before choosing what to work with. This definitely required that they think their idea through, and PLAN well for making it.

With the challenge spanning 4 weeks, there was ample opportunity for the students to look up ideas on the internet. This has always been something I’ve been okay with. Rather than labeling it as an attempt to “lift off” someone else’s ideas, I look at it as proof of the student’s interest in solving the challenge, a validation that he thinks about his design outside of the “makerspace”. And that is a good thing according to me! We live in an information world today where there is not only a wealth of it but there are so many easy ways to access it. As long as the student acknowledges the source, and doesn’t try to pawn off the idea as his own, I only see benefit in exploring the world wide web. 🙂

A few students took off on a wildly imaginative track, thinking in terms of electronics capable of sensing the texture and colour of the coins. With effective research, suitable materials and components, and probably some intellectual guidance, this idea could have taken form into a working solution. But given our material availability, and the fact that this was not really a “research” project, I had to keep egging these students to think in terms of other measurable physical differences between the coins. Soon enough, all teams figured out that “size” was the physical criterion they needed to use, to distinguish the coins. They understood that any solution would need to involve holes that were sized according to the three coin denominations. Following this, they all set out to cut holes of varying dimensions for the different coins to fall through. Interestingly, the material of choice for every group but one, was cardboard. I am guessing that Google search probably had a role to play in this.

Even after figuring out that they needed three different sized holes, it took a lot of thinking and trying, to understand that the holes had to be positioned in a certain order, and that the coins should be allowed to roll over the holes only in this order. While some groups went with square holes with sides equal to the diameter of the coin, some decided to be adventurous and try cutting out circular holes. Since the coin dimensions were pretty close to each other, the cutting had to be extremely precise. This learning came the hard way to most teams. Only after making several unsuccessful versions of the cuts, did the teams realise the value of clear outlines, and good cutting skills! On an average, every group made at least three attempts at the cuts, as even small errors translated to coins falling into holes not designated for them.

A great example of the “CREATE” -> “TEST” -> “IMPROVE” cycle in operation!

As the students kept experimenting, there were lots of light bulbs turning on around the room. Teams realised the need for the holes to be on an inclined plane, they understood the importance of having some sort of track to guide the movement of the coins, some even picked up on how the choice of ramp incline not only influenced how smoothly the coins moved, but also how many errors occurred!:)


90% of the designs involved a ramp, with 3 different sized holes. One team had smartly decided to make only two holes, and let the third denomination roll off the edge of the ramp. Given the difficulty in cutting accurate sized holes, this was definitely a smart call to take. One other group had gone with a completely different idea involving 3 stacked cups, each cup with one sized hole cut onto its base. Multiple coins could be put into the top cup at a time, and a shaking action similar to that used with a sieve would cause the different denominations to separate and collect in each one of the cups! While this was an innovative idea, there were some implementation issues that caused the design to not function as intended.


All in all, this was an exciting first challenge. The involvement, concentration, and determination to get their designs to work was exciting to watch! As planned, we wrapped up our session with each team presenting their design, and sharing their experience and learning with the rest of the class. I must admit that I got so involved in this activity, that I ended up making my own design. 🙂


For one, I wanted to understand how difficult the task really was, but I also wanted to put together an exemplar design chart that would document how I flowed through the Engineering Design process when I designed my solution. I was hoping that this would serve as a guide for their future designs tasks.

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