B - Additional research data

Private Logbook

Extra on what happened during the experiment

Lesson 1: 30 January 2020 (Thursday) 

After lunch, the team went on a hunt in the canteen to find bacteria. Our original plan was to ask the cleaner uncle. To our disappointment, the cleaner had already thrown the water away in the morning. We huddled and discussed what other alternatives were still possible. 

At that moment, Howie noticed the canteen vendor at the Chinese rice store used a cloth to wipe the food from the table. Beaming with hope, he suggested extracting bacteria from the cloth. We approached the canteen stall and politely asked for his table cloth. To our delight, he agreed. As it was dry, we added a little bit of water at the sink and then squeezed it out into a bottle we prepared. We were glad to have attained a source of bacteria from the canteen, but the sheer look at the yellowish-coloured water makes us feel nauseous. 

We proceeded to the Biology lab. Since the majority of the students were carrying out their experiments in the physics lab, the lab staff helped us bring our materials there. We shared our materials with another group after discovering they were doing the same experiment. Think win-win! 

During the teacher's briefing, she suggested using an alcohol lamp by lighting up the alcohol lamp to create an updraft so as to prevent dust from entering the Petri dishes. Another recommendation was to sterilise the tweezer after placing a soaked sterilised filter paper disk by putting it above the alcohol lamp. This helps to prevent different soaps from mixing. 

We made our amendments in the proposal before proceeding the experiment. We were sad that we forgot to bring tape to label the Petri dishes, but the lab staff said permanent marker was fine. One thing that we had to take note of was that we had to spread the bacteria by applying it line by line. This ensured that an equal amount of bacteria was applied at all sides. To help us document the process, Yeji video recorded the entire experimental procedure. 

Everything went well except for wrapping the petri dish with the parafilm. It was a chore as after pulling it halfway, we would use too much strength and break it into half (cause). Another problem we encountered was when we stretched the parafilm around the same petri dish, it fell out several times. (problem)It was frustrating! We realised that the cause of the parafilm falling out was because we did not stick it properly onto the side of the dishes. (cause) So we slowly stretched other parafilms and pressed it onto the sides of the petri dishes. (solutions) After finishing with the experiment, we followed the lab staff into the Biology lab to put the Petri dishes into the incubator.  

Lesson 2: 31 January 2020 (Friday)

When school was over, we went to the Biology lab to check on our results. After the lab staff took out the Petri dishes, we went to see the results of our experiment. 

Our guess was incorrect. We assumed that dettol was more effective but it turned out the soaps were better at killing germs, especially “Clorox”. 

However, one thing that went wrong was that the sterilised paper disk that was soaked with “Jif” was too wet, and hence it slipped out of place (problem and cause) We decided in the future, we would check if the each paper disks are in place, and equally soaked with each substances (solution) . While part of our experiment failed, we learnt to be more careful when placing the paper disk into the Petri dish next time. 

Lesson 3: 03 February 2020 (Monday)

Since we were able to finish our first experiment so quickly, our science teacher, Mr Tan, allowed us to do a second experiment. 

Our results on Friday showed us that “Clorox” was most effective in killing the germs. Hence, we decided to see if a lower concentrated “Clorox” would be equally effective in killing the germs. This could cut cost significantly, as we would only require half of our resources. From a practical standpoint, this would mean that normal users could save much money by using the right amount of “Clorox”. Too little would not be effective, while too much would be a waste. 

So, we were excited to test out this hypothesis. Joel poured 5 different amounts of “Clorox” concentration into each respective test tube. Howie used a permanent marker to label all the test tubes. Yeji filmed the whole process. It was a team effort. 

Lesson 4: 04 February 2020 (Tuesday)

As we were unable to finish the experiment on Monday, we had to continue with it today. Unfortunately, Yeji had to attend a competition, so only Joel and I were able to work on it. 

Other than soaking the sterilised paper disk in the different “Clorox” concentrations, we also tested using “Jif” because it was the only one that failed in the previous experiment. This would confirm our suspicion if “Jif” was truly ineffective. 

During today’s experiment, we made many errors. Not only did we break the parafilm several times as we could not control our strengths stretching it, but our sterilised paper disk also kept flying away - despite us putting a weight on it. In addition, Joel accidentally spilled the non-concentrated Clorox on the table and onto his bag. If only we were more careful, these problems would not have occurred (problem and cause and solution)  Nonetheless, we were able to finish the whole experiment by 3pm. 

Lesson 5: 05 February 2020 (Wednesday)

The day of the results has come. The test outcome was not as expected. The Jif was not effective in killing the bacteria and the ​4⁄5 Clorox concentration was almost as effective as the ​5⁄5 Clorox concentration. However, Joel realized that reusing the bacteria used for experiment 2 was a mistake because we placed it in a freezer after the first experiment. Some of the bacteria will die due to the cold. The surviving ones would then dominate the area. This makes our experiment unfair (problem and cause). On top of that, Mr Tan recommended us to do a five days observation so that we will know the growth of the bacteria in a period of time. With all of these, we can only redo every single experiment on Monday to have a daily observation. So, instead we spent the time editing our proposal.

Lesson 6: 06 February 2020 (Thursday)

We continued editing our proposal. As we were amending the report, we wondered if we could use the second experiment to prove that people can much less Clorox to achieve the same effect of eliminating germs. This would minimise usage of these cleaning agents and save resources and money. Especially in situations like COVID-19, many things are in short supply. This would have a direct impact on the cleaners who use these cleaning agents. On the topic of COVID-19, our testing equipment like the incubator are kept in the school, and we are not allowed to bring it home. If the school shuts down, we would not be able to continue our experiment. Hence, we needed to do our experiment ahead of time. We also felt that we should do two sets of the two experiments. So, even if both experiments fail, we still have another backup set and not need to wait for another week to do it. This made us slightly more relieved. 

Lesson 6: 10 February 2020 (Monday)

Earlier today, Mr Tan recommended us to finish the experiment by this week. So, we rushed into the lab and quickly got started. As we have to observe our results for 5 days, we decided to finish it by today. We only had 40 minutes to complete the experiment. Even though we knew the procedure well, completing two experiments in this short amount of time was a challenge. 

Instead of working in teams to maximise the time, we just did our parts. Howie tackled the experiment on the effects of different chemicals on the growth of bacteria while Yeji and Joel did the other one on the effects of different concentrations of Clorox on the growth of bacteria. This caused us to be frantic. As we were in a rush, we made some errors like denting the agar jelly, forgetting to take pictures of the petri dishes and dropping the paper disk outside the petri dish. However, we were able to complete it just in time. In the future, we could have prevented this by collaborating more so that we can cooperate and finish our experiment on time without the need of rushing. Now, we wait for one day and observe for the rest of the week on the success of our experiment. 

Lesson 7: 11 February 2020 (Tuesday)

Howie was absent today. So, Yeji and Joel went to the incubator to collect our petri dishes and to see the
results. The results were all successful except for the petri dish with undiluted clorox. The cause of its failure was due to cross contamination. There was fungus growing in the petri dish, causing the killzone to be small (problem and cause) . However, luckily, we had prepared a backup petri dish and was able to know the results. We spent the day taking pictures and measurements of the killzone for each dilution and bleach. “JIF” and “Mamalemon” had no effects. On the other hand, “Clorox”, “Mr Muscle” and “Dettol” had the best killzone. All three of them had similar killzones. Joel continued to compare the killzones while Yeji
focused on editing our video. 

Lesson 8: 13 February 2020 (Thursday)

We made a surprising discovery today. We were surprised to see that the “Dettol” killzone grew smaller.
This implied that “Dettol” was only effective in killing bacteria for two days. However, the other petri dishes
killzone remained the same, which meant that the other killing agents were still present in the petri dish.   

Lesson 9: 14 February 2020 (Friday)

Yeji and Joel were unavailable today, so Howie recorded the findings by himself. However, he forgot to
put the petri dishes on top of a black board. Also, the Astronomy club students needed to use the lab as
soon as possible. Hence, Howie had to leave the lab early and unable to see / record the killzone. We
were disappointed, but we still had an opportunity to do the repeat experiment next week. 

Lesson 10: 18 February 2020 (Tuesday)

As all three of us had to stay back for respective things, we could not start the experiment yesterday.
Initially, I thought we could get our hands on the experiment. To our horror, the lab has run out of small
petri dishes. Without the petri dishes, we do not have the equipment to put our paper disk soaked with
their respective chemicals in. Hence, to our disappointment, we could only start with it next week. To
prevent getting this problem again, we requested for the petri dishes today. By doing so, the lab would
have adequate petri dishes for us by next week. However, this allowed us to edit the uncompleted parts in
our document.   

Lesson 11: 25 February 2020 (Tuesday)

One week has passed. We have been working on our proposal for the past week. We collaborated well
today and had no problem with our experiment. However, we had a slight problem. Initially, we were
supposed to take pictures of our petri dishes. However, after the experiment, Howie and Yeji felt that it
was redundant to do it as we only need the data after the bacteria started growing. Joel insisted on taking the pictures. This caused conflict in our group. Our argument could not be stopped until a friend of ours came in to stop our argument. In the future, we can prevent conflict by using the 5 habits in the “7 effective habits”. Each of us should understand other people’s perspective before voicing out our own opinions. This will allow us to be calm during every discussion.  

Lesson 12: 28 February 2020 (Friday)

After observing our repeat experiment on Tuesday, we were astonished that the Dettol’s kill zone was much smaller than the previous experiments we have done for all the days. We must have made a mistake along the way. If we have the luxury of time to repeat this experiment again, we can improve this by making sure that the paper disks are soaked with a fixed amount of volume. When it is too wet, instead of applying the excess at the sides of the bottle, we should redo it again. This will prevent taking out too much of the liquid in the paper disk. We should also redo when we apply too little to prevent adding too much liquid in the paper disk too. This will allow us to have more accurate results. 

As tomorrow is the submission of the final report, it is technically the last day for experimentation. All three of us had fun during the experiments even with the little hiccups along the way. We hope we can have ISS again in the future.