Another year another science week (2026)! By Dr Katherine Brimblecombe

Once again, I had the honour of being invited to my son’s primary school to talk about my job as a scientist. I spoke to ~ 50 students aged 7-11. This years’ theme was “Curiosity: What’s your question?”. I didn’t find this theme very helpful to plan my visit so I decided to just ask the teacher what they’ve been studying in their science lessons.

The students had been studying digestion so I decided to speak about how our brain is fuelled and how we have a “second brain” in our tummies!

I started by asking the students to share with me their favourite facts that they learnt about digestion. Unsurprisingly this was mostly about poo and wee! But it’s important our junior scientists learn that there is nothing shameful about the human body, no matter how gross it might seem!

I then went on to share with them some micrographs of the small intestine and colon. We spoke about how the surface is folded and looks like fingers to provide a bigger surface area to absorb the nutrients. We then spoke about how the muscles push food along the intestine and how special gut neurons control this movement. We did a live demonstration of peristalsis with two rows of students acting as muscle and two inner rows acting as neurons, and me as the food passing through the middle two “nerve cells” rows. I explained that when the food pushes past the nerve cells, they are stretched, causing them to send a “squeeze” signal to muscle cells whilst telling their neighbouring nerve cells to “shhh”. The “shhushed” nerve cells then tell their muscle cells to relax so the food can be pushed along. This caused a lot of fun and noise, but I’m not sure how much the general principles were passed on…. I think the children were (understandably) reluctant to “squeeze” me! Oh well, live and learn!

We next spoke about how the nutrients from our food are used to keep the body healthy and give it energy. We spoke about how our brain is only 2% of our body but uses 20% of our energy. To explore this idea, I had a piece of playdough and asked them how much they thought 2% was, we played a game where I would pinch off different amounts of playdough and the students would shout “higher or lower” to guess how much was approximately 2%. I also had a cardboard pizza and asked the students, if they ate the whole pizza, how much of the energy would be used by the brain? There was a surprising number of “all the pizza” answers in response … but we used scissors to cut up the pizza into 5 pieces to see how 20% looks.

We next spoke about how the nutrients travel from the blood into the brain. I explained how we don’t have blood in our brain, and how our brain is protected from bumps and scrapes by our skull but protected from things within our bodies by the blood brain barrier. We spoke about how some nutrients can pass straight through (salts) and some need to be actively transported by special carriers (e.g. sugar).  I used the classic “fit the shapes into the right hole” baby puzzle to demonstrate this. Lastly, we spoke about how some molecules can pass straight through the blood brain barrier, by comparing what happens when you add cinnamon to water or oil!

As always, it was an exercise in finding out which communication strategies work, which analogies hold water, and how to hold the attention of an extremely honest audience!

Thanks again to Prof. Zoltan Molnar and Prof. Stephanie Cragg for letting me borrow their model skull and teaching slides respectively. 

 KRB April 2026