Teachers will need to follow the directions on the gelatin package the day prior to class. Pour the liquid gelatin into each petri dish. The dishes should be half full. Be sure to cover the dishes once you pour in the gelatin.
Students will discuss the achievements of Scientist Louis Pasteur who developed the underpinnings of modern biology and germ theory. He developed a process known as pasteurization. His work proved that bacteria and fungi from the environment were causing infection and spoilage.
- Two petri dishes per student
- Dirty little hands 🙂
- In the Before box ask your students to draw a picture of bacteria. Bacteria are quite diverse so students can be creative here.
- In the After box, ask your students to draw a petri dish with nothing growing in it. Perhaps just a circle that is empty inside. This represents Pasteurization or destroying the bacteria.
- Louis Pasteur was a teacher. One of his student’s father asked him to help him with a problem. He made wine from grapes and had always had good success. Lately, the wine was going sour in the vats (very large holding tanks) and was unusable. Pasteur looked at the wine in his microscope and could see tiny objects dancing around. It was Bacteria. Pasteur conducted several experiments and found that when bacteria are heated they die. We can heat food to kill harmful bacteria. Many bacteria are very good for us. Bacteria in fresh milk, for example, is filled with good nutrition. Other bacteria is quite harmful. We must fully cook chicken, for example, because it could contain deadly bacteria.
- Discuss the importance of washing hands with your students. Washing hands removes many harmful bacteria. Anti-bacterial soaps and alcohol based cleaners kill good bacteria as well as bad.
- Discuss potentially bacteria laden places in the church or your home.
- Give each student two petri dishes.
- Students should tape shut the first petri dish without touching the gelatin. Students should write their name on the dish. This is their bacteria free dish. Since the gelatin was boiled it should not have any bacteria. Explain again to your students that the heat kills bacteria.
- Give students a Q-Tip. Talk with your students about what they will sample. Door handles, toilet seats, floors, bottoms of shoes, hands, doors… Try to get as diverse as samples as possible.
- Students should rub the Q-Tip on their sample and then rub it in the second petri dish.
- Students should tape the cover on the second dish and write their name as well as where they sampled.
- Teachers, please ask parents to email pictures of their petri dishes to firstname.lastname@example.org