Virtual School has challenged the way we teach and learn. This is especially true in science where experiential, inquiry-based learning is at the heart of the learning process. To be successful our community must be willing to persevere and adapt. Simulations and thought-experiments have become increasingly important, but we must not forsake physical experimentation that produces empirical evidence.
There are many simple, yet impactful, experiments that can be performed at home with common household products. Making homemade Petri dishes is a straightforward, yet powerful activity, that can be adapted for science students from Pre-K to Senior School. This activity is especially relevant given the COVID-19 pandemic (caused by the coronavirus, SARS-CoV-2), as it can help contextualize essential practices like hand washing for younger students.
To make these dishes you will need:
- 250mL or 1 cup of boiled water
- 2 pouches gelatine
- 1 low-sodium beef bouillon cube
- 2 tsp sugar
- Measuring spoons and cups
- Mixing bowl
- Several shallow containers, such as a bowl or Tupperware
- Lids or plastic wrap for containers
- Q-tips or cotton swabs
See linked video above for instructions on how to make plates.
Agar plates, like those created in this activity, are used by microbiologists to study bacteria. You too will be able to grow bacteria on your homemade dishes. Eventually, your dishes will be contaminated by additional microorganisms such as molds and yeast (both of which are fungi). While viruses can be found on these dishes (remember, viruses are everywhere), they will not grow on these dishes in the same manner as bacteria and fungi. Viruses need a host cell to replicate in.
Suggested applications for students:
- Make dishes with your students. Then have them pick the areas of the house they are curious about. Set a time of day when they can collect data on what is growing. Data can be a coloring activity, drawing, or photographs. Older children can research what type of organisms they see in their dishes. The American Museum of Natural History has some excellent resources for this.
- Describe the importance of hand washing. While these dishes are designed to grow bacteria, they will grow other initially undetectable organisms as well. Have a conversation with your children about how small (and seemingly invisible) things like bacteria, fungi, and viruses are everywhere, which requires us to wash our hands to stay healthy (and keep others healthy). The Centers for Disease Control and Prevention has some excellent resources on how to make this fun and relevant for children.
Middle and Senior School:
- Have your student investigate the biochemistry of soap and how it works to kill viruses.
- Encourage them to investigate the life cycle of a virus.
- Have students design their own experiments to investigate factors affecting microbial growth. This will help them with terms like independent variable and dependent variable.
Some suggested independent variables (what is changed by the student) are:
- Amount of salt in dishes
- Amount of sugar in dishes
- Amount of sunlight
In this case, the dependent variable (what changes in response to the independent variable being studied) would be microbe growth.
Homemade Petri dishes are an excellent way to keep science hands-on during Virtual School. Furthermore, it shows students that microbes are everywhere. This is an important lesson and one that can help students use their hearts, minds, and hands to keep themselves and everyone around them healthy.