Professor in the classroom

News - 14 May 2020 - Secretariaat Sanitary Engineering

by Merle de Kreuk

TU Delft has reached the age of 178 and celebrates this occasion with Delft primary school pupils. On Wednesday 29 January, 25 TU Delft professors gave a guest lecture to pupils from group 7 and 8 at various primary schools in Delft as part of Meet the Professor, an event organised by the WIJStad programme and the TU Delft 'Wetenschapsknooppunt'.

When the major of Delft, Marja van Bijsterveldt, entered the city hall on Wednesday morning 9.00 a.m., she found a bunch of professors in toga, eating croissants and sipping their coffees. I caught her remark “wow, this is unusual…”, and indeed, it was. That morning, we were dressed up, with 25 professors, to teach a lecture at a primary school in Delft. From the city hall, many professors took their bikes to travel to ‘their’ primary school. Since I brought a bucket of sand, one of gravel, and many cups, spoons, some activated carbon and cotton wool, I took my car. However, walking in toga through an early morning Delft was an experience by itself: tourists looking over their shoulder, and giggling students unchaining their bikes felt awkward but special too.

And then the class began at CBS Het Talent in Den Hoorn. A group of around thirty exited 11 years old, being able to speak about pee and poo in class. It is not the first time I teach younger children. In 2017, I had the honour of lecturing in a “museumjeugduniversiteit” series, I was role model within the talent series of VHTO, and when visiting Hong Kong last year for the Dutch consulate, I had the opportunity to teach at two schools as well. Nevertheless, I always feel the excitement and nerves, stepping into a class of kids.

I first explained what sewage is, with the big yuck factor for all of them, why we need to clean it before it goes into the surface water and how it is treated at a sewage treatment plant. Many questions were asked and experiences shared by the children, from toilet visits to visits to the local sewage treatment plant Harnaschpolder. Just before they became too restless, we started with the buckets of sand and gravel and the muddy brown water I prepared early morning. My main message was: build a filter to treat this water, with some minor instructions, but with the main message: “just try with the materials you have, and think a bit before doing”. Especially the last bit worked in some teams better than in others, resulting in clogged filters, sand washing out from the bottom, but also perfectly filtered water. Of course we discussed why you cannot drink this filtered water and what else would be needed before it would be safe to discharge, if it would have been real sewage. Addition of the activated carbon and filtering again removed some of the colour and one of the more serious girls made crystal clear water: they convinced me it really was their filter and not tap water. And then the incredible moment, when one of the girls asked: “do you have some material left I can take home, so I can try this afternoon once more with my mum?”. This, and the 60 sparkling eyes, is why I love to volunteer for these occasions.