AI That Grades: How Two Students Built an Automated Marking System - S2E2

In this episode, we sit down with young South African innovators Gustav Heesen and Johan Vorster, along with their parents, Heinrich and Lianne, to discuss their remarkable invention, "Expobot". We dive into how they used N8N, Docker, and AI to build an accessible, fully automated test-marking system designed to help teachers in overcrowded classrooms get their time back, delivering personalised student feedback with an impressive 95% accuracy rate.

We also celebrate their incredible journey, from being the first Grade 7 learners ever to be named Overall Winners of the Gauteng North Imbewu Science Fair and placing as Second Runner-Up at the National Imbewu SAYESS, to earning an exclusive invitation to represent South Africa at the 2026 Genius Olympiad in Rochester, New York. Applied engineering and STEM enthusiasts will truly value hearing how these brilliant minds leveraged digital innovation to solve a practical, real-world problem.

Support Gustav and Johan’s Journey to New York! We are helping the family spread the word to people who care about STEM, education, young innovators, and practical support for South African learners. They are currently running a BackaBuddy campaign to raise approximately R120 000 to cover travel and participation costs for the students.

If you'd like to support the next generation of STEM innovators, any exposure helps, and even small donations make a massive difference!

Helpful Links & Contact Info:

• Donate here: https://www.backabuddy.co.za/campaign/genius-olympiad-finalists-help-us-get-there
• Watch the Project Video: https://www.youtube.com/watch?v=YN_rT_ieRNU 
• Get in Touch: For CSI, philanthropy, or innovation support, you can reach the parents directly. Lianne Heesen can be contacted at 082 094 3681, and Heinrich Heesen at 072 211 3960.

Transcript

(0:00 - 0:31)
(Farm animal sounds and theme music)

Host: Hello, and welcome to the Agricultural Engineering Podcast. This podcast covers all aspects of agricultural engineering. It is produced by the South African Institute of Agricultural Engineers. We encourage you to tune in and explore the exciting world of agricultural engineering with us. My name is Khuthadzo Ntsuwe, and I'm your host for today's episode.

Today we are featuring a story of innovation that starts in South Africa and has the potential to change classrooms across the globe. I am thrilled to introduce two exceptional young South African students, Gustav Viessen and Johan Vorster. These two have achieved something truly remarkable. They became the first grade 7 learners ever to be named overall winners of the Gauteng Mbeu Science Fair, later placed as second runner-up nationally at the National Mbeu South African Science Fair, and have now earned an opportunity to represent South Africa at the 2026 Genius Olympiad in Rochester, New York. Accompanying Gustav and Johan is their parents, Henrik and Leanne Viessen. Welcome to the Agricultural Engineering Podcast.

Student 1: I'm really grateful for everything that you guys have done and that we can be on this podcast and to represent South Africa. It's really an honor.

Host: Gustav and Johan, let's talk about this solution that you came up with that got you to the 2026 Genius Olympiads that are taking place in New York. What is it about?

Student 1: I would like to say that our project is about AI test marking. So, we saw that a lot of teachers, especially in our school and other schools, they spend a lot of time marking, and sometimes they don't have enough time to teach us effectively because they need to mark the tests. And also, it is slightly inconvenient for them to need to mark all these tests, and we know a lot of teachers really don't enjoy this job enough.

Student 2: And what's certainly also very common is if you just ask when you're receiving your tests, the teachers would immediately get frustrated because it's such a negative connotation of marking tests. But, um, so we wanted to solve this for them, and also what many people would immediately pick up on is that you could just ask ChatGPT or OpenAI to mark a test individually. But of course we did factor this in and there is still a specific reason you would use ours. Yeah.

Student 1: So, we used N8N and Docker to initiate a workflow that starts at a Gmail trigger. So you send images of a test with a memo to the special email account called expobot2025@gmail.com and then we... that email account will reply with a test being marked and ready with a breakdown and gives you personalized feedback on every question, correct or wrong, and why. So it's actually quite accurate.

Student 2: We have multiple test marking agents, multiple reading agents, and a moderator that helps to pick up on prompt injection. So um, well to be very clear on that, there's no digital shift in how the tests are written. There's no um, certainly we'd still, as it is today, would still write tests, the only difference is that teachers will then send in the tests via email and it would then be marked by an AI. And as Gustav said, there are specific moderators and multiple image analysis agents at each step. The agents just being the different AIs which work in tiny modules who then... there are multiple different agents allocated to a specific task to improve the accuracy.

Student 1: So, we can say the accuracy is good and go on like that forever. But what actually means something is the numbers. So we tested this pure Gemini and ChatGPT without giving them a memo and making their own memo. That got about 70% accuracy. Then, when... so that means that 30% of the questions were marked inaccurately, so that's almost one in three, which isn't acceptable. And with our workflow, we succeeded to be able to have a 95% accuracy, which is about in line with what a teacher has.

Student 2: Yes, and also what's very important here is that it makes a massive difference whether you give the AI a written or hard-coded memo or not. So at the start we experimented with just ChatGPT making up a memo, but this is much more inconsistent. And it is, as teachers already would set up a memo so it can be corrected and see if everything is aligned. But so they would still set up a memo and then drop it into a Google Sheets folder, a specific one, the children are not able to just find it and change it, and then the AI would fetch data from there.

Host: That is a very important solution that you came up with, because of course we want our teachers to spend more time in class with their students. So, explain to me, once I send that email to the Gmail account you mentioned, what happens next?

Student 1: So, it's all automatic. We don't have to move anything from the Gmail to the workflow. It automatically picks up that there is a Gmail that's been sent. Okay. Then it filters the Gmail to make sure it has no errors and is in the correct format. Yeah. Then it analyzes the images that were sent, with multiple analyzing nodes and then one node that decides which analyzed the best. Yeah. Then it will go to mark. The three different analyzed tests. So now in text format, not anymore in the picture format. Yeah. And it also has the memo which it gets from the Google Sheets. Then it uses all that information to mark the test two different times. Then those, the output of the two different test markers goes to a moderator. And this moderator will decide and also mark it in its own test, just like a teacher would have a moderator that checks her. Yes. And we found that this moderator significantly improves the accuracy of the workflow overall. Then it will have another workflow that drops it into a Google Sheet in a class list with all the children's marks and send it back via email to the account that sent it.

Host: This marking system, is it 90% accurate for any type of assessment irrespective of complexity? I'm just asking for somebody who may be interested to use the solution. Does it assess anything as long as there's a memorandum?

Student 2: There's no specific subject or level. It's not that it needs a, if it's a creative writing obviously it can perfectly mark that, and the memo doesn't then just need keywords for example, it doesn't have to be word-for-word what the memo says. As a teacher would also mark they look more or less along the lines. And certainly if a memo is provided, I mean since AI reads the entire internet, as long as it's written down somewhere and the AI has context for it, obviously if it's context-specific and it's for example only true in your region it might mark incorrectly. But in most cases it would definitely be able to see how it compares to the memo and give a very accurate mark. Especially if it has the memo.

Host: What is exciting you most about representing South Africa at the Genius Olympiad in New York? I mean, the list is long, you are going to be among geniuses from all over the world, and what is it that you hope to learn and take away from this experience?

Student 1: I think definitely it will become even more significant when we are there. For me at the moment, I see it as just another expo, but I'm sure once you fly past the Empire State it will definitely, you'll realize where you are and you will be there. So no, it's definitely, it's incredible to think that South Africa only sent so many people and now you're going to a place where anyone from the entire world, if you think you have family or friends in another country, they can also be there. It's not limited in any way. So it's very special to think that.

Host: So before we get to Gustav, Johan, how many expos are you attending or participating in in one term or, what is happening?

Student 2: Um, there's, I know there's the Eskom Expo, and then there's the Mbeu Foundation Expo. We didn't compete in the Eskom one yes, last year, we only did the Mbeu one, which there was a North Gauteng competition, not a Gauteng competition that then went straight to a national competition.

Host: Interesting. I'm happy to hear that. Gustav, do you want to tell us what this means for you?

Student 1: Yes, I also want to add I just think this is an incredible honor to represent South Africa and we really wish to inspire our grade and all the other children around us to use and be creative and actually work on their ideas because it can pay off. Before we decided to do the expo and work really hard on this, we didn't know that we potentially could be good at this, and once we tried we saw that this is one of the things that we really were interested in and really liked. And once again it's an incredible honor and we really look forward to representing South Africa at the Genius Olympiad.

Host: Alright, Gustav and Johan, thank you very much for being with us today at the Agricultural Engineering Podcast. It was nice talking about activities in STEM with you guys. Any last remarks before you go?

Student 2: Thank you very much for this opportunity. We really do appreciate it. And we hope by this podcast to inspire thousands, hundreds of other people in our age group to really use their ideas and be creative because it can become something in the real world. And also, I think for anybody, any future scientists, anybody who'd like to do this, it doesn't happen the first time, this is the second time we do this expo. And it definitely takes a bit of practice, but you should never think that you can't do it before even trying. And um, thank you very much for having us here on the podcast. We look forward a lot to representing South Africa.

Host: So let us hear the opinions of the parents. With us is Henrik and Leanne, who will be telling us about what they think about these opportunities. Henrik and Leanne, tell us. How has it felt to see your children's projects being selected as a finalist for an international competition? What does it mean for you and for their future?

Leanne: Like I was saying to them, I looked at that list of projects that are going to the Olympiad, I'm like, this is such a great opportunity for them. How do you feel?

Henrik: Joh, so many tears. We cried, we're not gonna lie. I think we're still... we're still crying. I think we're still in disbelief, we're double checking the list every few days to make sure it's, it's really there. So we're really proud. But it is, it's really unexpected, so we didn't even know that it was possible. Also, I mean, these essentially primary school kids, because it was their project in grade seven that they're going for now. Um, so no, we're very proud. And we also saw how hard they worked because they worked weekends, in and out, and at night, and on WhatsApp videos, they talked. So they really did put in a lot of effort. It's not like it wasn't a quick thing. So we are happy for them that it paid off and that they have the opportunity to go overseas for the first time in Gustav's life of going, um, and actually, you know, fly on a plane and go and meet kids from his, his peer group, but globally, and see actually what the competition is like and what ideas they have. So it's very, very, um, we're very grateful for the opportunity.

Leanne: I can't add much to that, but we're, we're, I just wanted to say, it the stars kind of aligned. Johan's mother works in an environment of understanding the outreach required for all the schools to really make stuff work. So Johan really understands that problem. And Gustav came with, he understands the AI stuff because that's my job and I talk about it a lot. So it was kind of influences and the influences got together and they, they came up with this project themselves. Uh, and you know, I just gave them the tools and then they, they ran. You know, and they really did something extraordinary. So, um, we're very proud of them and it is a great honor that we're like, suddenly we're representing South Africa, we're going somewhere to do that.

Host: We are sharing this story today because the family is currently trying to get word out to people who care about STEM education and young innovators for that matter. We know that participation comes with significant costs, that is for flights, accommodation, registration and what not. Could you share what kind of support you need to make this journey possible and how can our listeners help?

Henrik: So, anything really, um, would be really helpful. So we've set up a BackaBuddy campaign for them to try and raise the funds. It works out a few, so the participation in the expo itself has quite a high cost, and then the registration and um, the flights and the visas and so it comes to quite a lot, especially because they are under age and they also need chaperones to go with them, to be able to go. So in the end there's four people going. So it's Johan's mom is going with him and then Gustav's dad is going with him. Um, and all in all we've set up the BackaBuddy target for R120,000 for the two of them, so the parents we are we are paying our part. For the two of them, um, it comes to about R60,000 each. We've already sort of um got a couple of friends and family to donate to the BackaBuddy who is supporting them. Um, and there's been a few companies who's also contributed. So we are trying to see if we can um, get to that target for them to be able to go. Um, so if anybody uh does have a spare rand or two to contribute we would really appreciate that or just sharing the campaign and their story as well and trying to get exposure.

Host: Thank you Leanne and Henrik for that. Just to clarify, when is this competition happening?

Henrik: So it starts on the 8th of June. So they would need to fly a couple of days before then and then they return on the, I think it's about 5 days, so a week. We are allowing just just afterwards... but we're trying to make sure we get everything before so we can get that. The contributions we have already has already helped because we've, we're getting everything in place. Yeah.

Host: Well, you have heard from the young learners who have developed a machine learning tool which is an AI test marking system, Gustav and Johan. And also their parents who are talking to the STEM community, philanthropists, and anyone who has a rand, dollar, pound, any money to spare to make their trip to the 2026 Genius Olympiad possible. Please look out for the information in the description box, and thank you for listening to the Agricultural Engineering Podcast. Please do not forget to like, share with anyone who might have interest. With that said, until the next episode, it is goodbye for now.