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Thursday, August 16, 2012

Our First Experience With the Student-Designed Lab



Did you read my blog post from two days ago? In case you did not, here is a quick update:  I am trying to change the focus of my high school biology classes by incorporating more student-designed lab activities.  The previous post was about getting my students ready for their first attempt.

Well, today we have completed our first lab in which the student designed the lab from top to bottom.  I am happy to report that I am quite pleased with the results!!

For our first attempt, I gave the students a very, very, very simple idea to work with.  After all, the point of this lab is to learn how to design and carry out an experiment.  I asked my students to design an experiment that would test the effectiveness of different quantities of water on the germination of seeds.  Simple , right?  It turned out to be such a great idea!  There are limited options for the students and no advanced knowledge about the topic was needed.  The students only had these materials to work with:  Petri dishes, filter paper, radish seeds and a graduated cylinder.  Initially I did not include the filter paper, but we quickly realized that a small quantity of water would "pool " together in the plastic Petri dish, and we needed the water to spread out across the entire surface.  Students were instructed that if they lined the dish with a piece of filter paper, the water would evenly spread across the surface.

Radishes were a great choice!  They germinated within 24 hours, and I allowed my students to observe their germination rate every day for three days.  I had my students complete a lab report in which they had to design and complete the following:

  • State a hypothesis that is testable.
  • Write out detailed steps to their procedure.
  • Determine the independent and the dependent variables.
  • Include a description of their control and how it served as a control.
  • Include a description of their experimental groups.
  • Identify factors that must remain constant throughout the experiment.
  • Design a data table.
  • Graph their germination rates.
  • Form a conclusion based on the data gathered.
Below are a few pictures that I took during the lab activity:


The first dish on the left served as a control since these seeds received no water.  The other three dishes received varying amounts of water.

Some students elected to keep their dishes in front of the window....

.....while others elected to keep their dishes under a plant growth light that remained on 24 hours a day.  Other students placed their dishes in complete darkness.  

Light level was not a variable being tested.  Whichever light level the student picked, had to remain constant throughout the experiment.  The variable being tested was the amount of water placed in each dish.  

The only problem with this experiment was that some students had difficult reaching a conclusion.  They found that there was not that much difference between germination rates of radish seeds when given varying quantities of water.  

All in all, our first attempt at the "student-designed lab" when extremely well.  Most of the anxiety I have about allowing students to design the experiment is now gone, and I am very much looking forward to our next attempt!

Have fun teaching~


2 comments:

  1. I went to a workshop yesterday over notebooking in a science class, and the teachers who presented let us do an experiment and then design a new one to test whatever we wanted to test. Our district does that at the high school level, but at my level (K-4), it's not quite as feasible.

    One thing the presenter says she does with her students is lets them do the experiment, then they come up with questions about the experiment, via a I notice | I wonder chart. In a group, they decide on one question that they can investigate. She tells them what materials are available, and the students submit experiment requests. If the experiment is safe and doable in the amount of time available, she approves it, and the students are off and running! Each group tests something different, and then they share at the end of class. You probably already do this, but I just had to share it with you, since I'm still excited about the workshop! :)

    ~Mrs. K. from The Teacher Garden Blog

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  2. Thank you so much for your comments. I do indeed do just what you described. Since we have just started school, I guided the students with a beginning experiment that had few options. But very soon, they will design an experiment of their own choosing. This is great for our students but so difficult in terms of the time it takes to complete, and the large class size that so many of us face.

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