Petri Dishes
MS-LS1-1 Conduct an investigation to provide evidence that living things are made up of cells; either one cell or many different numbers and types of cells.
During our microbiome unit, we had our students grow petri dishes using a swab of one group member's hand. We kept the petri dishes incubated, and the students took the dishes out each day to count and draw their colonies. At the end of a week, students graphed their data to display how their colonies had grown over time. However, I don't feel like students got as much out of the activity as I would have liked. For this week's learning post, I would like to find another lesson that incorporates petri dishes in a more meaningful way.
After reading through a few lesson plans, I decided on one that I think would have created the most positive change in my classroom. The was presented by Teach Engineering and can be viewed here:
https://www.teachengineering.org/activities/view/nyu_bacteria_activity1
In this activity, each group had three petri dishes to track, as opposed to one: unwashed, washed, and sanitized. When swabbing the designated student in each group, the students first swab the unwashed hand of one student and roll it onto one petri dish. Then, group mates will wash one hand of the same student, and swab for the second petri dish. Finally, they will sanitize the second hand of the same student, and swab for the last petri dish. It's important to use the same student for all three dishes, because each person's microbiome is different, and carries different bacteria. By comparing the same student's hand when unwashed, washed, and sanitized, variables will be limited. I like this way of doing the lesson better because students have more to compare, and more data to record. They can see the change over time of the bacteria growth, and also compare the rate of growth between the three samples. One aspect that would be more challenging is that each group now needs three petri dishes as opposed to one. When my cooperating teacher did this activity, she had to purchase the petri dishes herself. Having to purchase three times as many for 140 students can either become very expensive, or groups of students would have to be larger. However, when there are more students in each group, each student has less of a role, and there is a greater likelihood for only a few students doing the work and then the rest copying from them. However, if the school provided the petri dishes, I think this lesson would be a much better way for my students to gain meaning from the activity.
During our microbiome unit, we had our students grow petri dishes using a swab of one group member's hand. We kept the petri dishes incubated, and the students took the dishes out each day to count and draw their colonies. At the end of a week, students graphed their data to display how their colonies had grown over time. However, I don't feel like students got as much out of the activity as I would have liked. For this week's learning post, I would like to find another lesson that incorporates petri dishes in a more meaningful way.
After reading through a few lesson plans, I decided on one that I think would have created the most positive change in my classroom. The was presented by Teach Engineering and can be viewed here:
https://www.teachengineering.org/activities/view/nyu_bacteria_activity1
In this activity, each group had three petri dishes to track, as opposed to one: unwashed, washed, and sanitized. When swabbing the designated student in each group, the students first swab the unwashed hand of one student and roll it onto one petri dish. Then, group mates will wash one hand of the same student, and swab for the second petri dish. Finally, they will sanitize the second hand of the same student, and swab for the last petri dish. It's important to use the same student for all three dishes, because each person's microbiome is different, and carries different bacteria. By comparing the same student's hand when unwashed, washed, and sanitized, variables will be limited. I like this way of doing the lesson better because students have more to compare, and more data to record. They can see the change over time of the bacteria growth, and also compare the rate of growth between the three samples. One aspect that would be more challenging is that each group now needs three petri dishes as opposed to one. When my cooperating teacher did this activity, she had to purchase the petri dishes herself. Having to purchase three times as many for 140 students can either become very expensive, or groups of students would have to be larger. However, when there are more students in each group, each student has less of a role, and there is a greater likelihood for only a few students doing the work and then the rest copying from them. However, if the school provided the petri dishes, I think this lesson would be a much better way for my students to gain meaning from the activity.
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