Month: May 2018

Session four – preparing to share what we’ve learned

Week four of the science club was all about the children recapping on what they had learned in the previous weeks, and preparing materials for a show-and-tell with their families in week 5.

One group practiced arranging the organs of the digestive system. They managed to get everything assembled correctly in under 5 seconds! They also prepared a poster on the gut microbiome.


Working through how the digestive system works. Edible poo will be required next week!


Marine helped one group draft a scientific poster, to present the results of their farting experiments. The poster is going to be printed professionally to look like a proper conference poster. 🙂

We were really impressed with how much the children remembered from the first three sessions, and loved how enthusiastic they were to share what they had learned with others. They seemed to really like the idea of professional conference posters. This is something we will use with all groups for the next run of the after-school science club (June–July 2018).

Session three – why do we fart?

A lot of excitement from the kids and stress for me (Marine) the day of the farting session! The session on how our digestive system works the previous week had been a huge success, so the pressure was on to make this session fun and to keep the kids motivated and engaged.

Before the kids arrived, we prepared three “lab benches” with all of the materials for the experiments ready and waiting.

Everything ready for the kids to conduct their farting experiments.

To save time, all the dry ingredients had been weighed out in advance. The kids only had to pour the ingredients into the flasks along with the water. I deliberately placed the lab benches at the back of the classroom, so the experiments could be left to incubate without distracting the kids while I went through some of the theory behind the experiments and what they were going to show us.

When the kids arrived, I gave a short (5 to 10 minute) introduction to the session, during which the kids showed a lot of interest in the subject. Then we started the hands-on part. It was wonderful to see the kids helping each other and working as teams to set up the best experiments they could!

The kids carefully followed their protocol and shared the tasks among group members.

Each group managed to set up their experiments within 15 minutes, and all the kids were quite curious about what would happen next. Like true little scientists, the kids cleaned up their benches before returning to their desks! 🙂 They then sat to watch a video on how gas is produced in the large intestine, and I talked to them about what a hypothesis is and why replicates are important in experiments. They were quite pleased to find out what makes their farts stinky – sulfur. One of the boys said he knew why his Dad’s farts smelled so bad: he must produce a lot of sulfur because he eats lots of eggs!

While the kids learned the theory behind farts, their experiments were left to incubate.


A video explained why some farts smell while most don’t. I then talked to the kids about the hypothesis for our experiments, and asked them which balloon they thought would have most gas in it based on what we’d learned about how gut microbes produce gas from the food they eat.

After going through the theory and leaving the experiments to incubate for 15 minutes, everyone went back to their experiments, excited to see their results! The kids carefully measured the height of each balloon and recorded their results on a graph.

The results of the experiments showed that gut microbes produce most gas when they have a carbohydrate source (sugar) and warmth, conditions similar to those found in our large intestine.


Much to the team members’ delight, the yellow team (group 2) had the balloon with the most gas at the end of the experiment.

Session three preparations

When I (Marine) knew that I was going to have to take care of the third session “Why do we fart?” and it was going to follow on from the session where the kids made edible poo, I seriously asked myself how it would be possible to make my session as enjoyable and interesting for the kids as the previous week’s. My idea formed relatively quickly: some yeast (representing the gut microbiota), some sugar or flour (representing the different foods we eat), and some warm water in a flask, all topped off with a balloon. I knew fermentation of the sugar by the yeast in the flask would produce gases (farts!) and make the balloon inflate. And in my mind I could definitely see the kids enjoying the role of mini chemist and having fun with the inflating balloons, wondering whether they would explode at some point!

Combining food (sugar or flour), gut microbes (baker’s yeast) and water in a flask (the intestines) would mimic the way gut microbes produce gases responsible for flatulence.

I prepared my session by looking at some experiments posted on the Internet, and adapting what I found. Initially, the experiment I designed involved seven flasks per group of four students and was quite complex. However, following the first session, run by Holly and Grace, I realised I was being ambitious in what could be achieved in one hour, so I simplified the experiment. I wanted the kids to remember the main take-home messages of the session – that gut bugs make us fart, and they need food and warmth to do this. I had two practice runs prior the session, to adjust the quantities of ingredients needed for the experiment and to ensure the required results would be achievable within one hour.

Each group of four students would set up four flasks to determine what makes us fart. The first flask would contain warm (37 °C) water, sugar and gut microbes. The second would contain warm water and sugar but no gut microbes. The third would contain warm water, flour and gut microbes. The fourth would contain cold tap water, sugar and gut microbes. The kids would then put a balloon on top of each flask to capture gas produced. They would then be asked to predict what would happen in each tube during a 15-20 minute incubation.

Before the hands-on part of the session, I planned to give the kids a brief explanation about what flatulence is and why we fart, so they could understand what we were trying to do with our experiments. After the kids had set up their experiments, I wanted to take the opportunity to introduce them to the concepts of a hypothesis, variability and replicates. By discussing with the kids what would they thought would happen, I thought it would give them a better understanding of how gut microbes make us fart. The students would be split into three groups, each of them doing the same set of four experiments. This would allow them to compare their results, and understand variability and why repeating an experiment and taking mean results is more accurate than doing an experiment only once. They would also learn how to analyse and report their results.

At the end of the incubation, the kids in each group would measure the height of each of their balloons and record the results. They would then compare their results with those from the other two groups, and discuss the differences in results between each flask and each group.