Reading Apprenticeship Inspired Assignment or Lesson
Reading Apprenticeship Inspired Assignment or Lesson
Students are often challenged by the concept of serial dilutions. This activity allows the student to take ownership of their learning, incorporate their creativity, and practice a presentation without the pressure of giving a presentation in front of a group of people.
The students are encouraged to “read aloud” the procedure with a peer before recording their video. This helps the student gain a better understanding of the procedure. By teaching the serial dilution procedure in the video, the student demonstrates a deeper level of comprehension.
This video is due before we conduct other procedures that require serial dilutions. The goal is for the students to understand serial dilutions so that they can utilize that knowledge for more complicated procedures.
We do expect the students to have had exposure to serial dilutions in the prerequisite classes such a general chemistry. We provide them with a procedure and guidelines, but the student is expected to complete the assignment outside of class. To prepare the students, we do discuss measurements and consistency in those measurements. We discuss measurements used in science versus measurements used in US culinary situations. Previous to this assignment, the students gain experience in streaking for isolation and counting Colony Forming Units (CFUs).
I watch the videos to evaluate if the students are consistent in their measurements and if the students are able to correctly calculate the number of Colony Forming Units (CFUs) per milliliter in the original sample. If the student has any errors, the students are given feedback and then they are given the opportunity to correct their errors for full credit.
This activity allows the students to evaluate if their result aligns with what they know about growing bacteria on agar plates. They build on their previous knowledge about dilutions and then evaluate if their final count aligns with what they know about how dilutions enable accurate readings. They are also given examples of how understanding serial dilutions could be applicable at a future career.
The students model their thought process while reading a text aloud from their lab procedure, essentially "thinking aloud" to demonstrate the metacognitive strategies skilled readers use to comprehend a passage, allowing students to learn and practice these strategies. This helps students develop their own reading comprehension skills by making the invisible process of thinking while reading visible.
Laboratory Procedure for Serial Dilutions. Work with another microbiology student. Each of you will submit your video.
Directions:
1. Be creative! Make a video (YouTube usually works best-make sure you make it available to me) and post the link here.
2. Give details on what your solutions are and what the dilutions are (1/10, 1/100, etc.)
3. Please try to keep your videos to less than 5 minutes. 3 minutes are ideal.
4. You must show calculations. You can make up the numbers for the growth on the plates. 5 tubes/cups/etc. total.
Do an example equation if you use 0.1mL of fluid containing bacteria to your plate and have 75 CFU's at your 10,000 dilution.
5. Each of you must pick a section of the procedure and practice "think aloud". You read your chosen section of the procedure and explain what it means in your own words.
Additional Resources:
A. Using colored beads to do serial dilutions video
B. Extra Serial dilutions practice website
C. Bacteria Enumeration PPT
D. Serial Dilution: Definition, Purpose, Calculation
Student Examples (Can you identify what is missing/is incorrect?)
1. This video is not 100% correct. Can you evaluate what can be done better? What is missing? Example videoLinks to an external site.
2. Here is an example that starts out great, but does the math make sense? She states that the diluted plate has less CFU's than the original. What would you do differently? https://drive.google.com/file/d/1S67_pb2h3tobjRaQchAKtXmAdpjlh7Vr/view?usp=sharingLinks to an external site.
We chose these texts/resources to give the students the opportunity to learn the basics of serial dilutions then challenge themselves with more difficult equations, should they want that opportunity. The lab procedure for serial dilutions is available here.
