Building Evidence: Yeast is a Living Organism

The claim that Yeast is a living organism started the process of investigation. My budding scientists have been thrown into the evidence machine and are working like crazy to collect evidence (the fun part), discuss it (the hard part) and evaluate how the evidence can be used to support the claim (the teeth-pulling part). The week began with students returning to characteristics of life and determining what evidence they had from the first experimentation. Large whiteboards served as the platform for this session:


Groups ranked the strength of their evidence: (+) if they believed it to be strong, (-) for weak evidence and (0) for no evidence. Many groups were unsure at this point of whether or not they had strong or weak evidence and few students seemed willing to go out on a limb and support their thoughts. This is new to them…

During this process I tried a new technique of shuffling groups and it turned out to be effective. Group members counted off so that each was a 1, 2 or 3. Then, during the analysis phase, a card containing a number was pulled and the student with that number rotated to the next table. Later on as we continued processing information, this process was repeated. In both instances, new insight was brought into the group and by the end new groups were also formed.

The new groups then focused on two characteristics: responding to a stimuli and being an energy user. Their task was to determine how to design an investigation (based off of the initial day of of experimentation) to collect evidence. We haven’t kicked around official terms for variables but most were getting the idea of controls and manipulating variables. A few surprises popped up. Groups investigating energy decided to experiment with sugar, no sugar and in a few instances, salt. The inflated balloon has sugar, the other was without or with salt.


At the end of the week, a few groups began processing this information. My goal is to bring out the idea of a scientific community between the four classes. I want students to share information throughout the classes. We’ll try a combination of poster and tech-infused ways to share data. This time, I asked students to create a poster that included a quick visual of the set-up (different colors for the manipulated and controlled variables), key observations, and an explanation of how their evidence supported or refuted their claim.

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Parent Letter (8/29): End of August – Lots of experimentation

This year, one of my goals is to open up the possibility of dialogue with the parents of my students. I feel that this connection has been minimal in my teaching practice as I only meet with parents during conferences, random hallway bump-ins or if there are issues. I want parents to feel that they are part of the learning community that includes myself and their students. I plan on writing weekly emails as a way to open up this space. In the past, my blog updates have mostly been used by students and a few parents let me know that they read it. By having a message arrive in their inbox, I hope to become a bit more present. I get the feeling that as students leave elementary school, they slowly become disconnected. Gone are the expectations that teachers email or have weekly letters. I’m fortunate this year in that I’m teaching multiple sections of the same class which allows me to focus on one short message. We’ll see how it goes.

I hope that everyone has enjoyed the blue skies of the past week. Though the days became quite hot, many mornings began with a coolness that could be a sign of the upcoming season change. We spent a little time in class talking about seasons and I encourage everyone to have discussions at home around changes you notice on the rides to school, walking about or in other places. It is powerful when students build a strong connection with the environment around them.

In science class, we have worked on several experiments throughout the past week. Students are doing a great job processing information and planning new investigations. It is hard work! They are being asked to evaluate the evidence gathered in experiments to support or refute the claim that yeast is a living organism. For many students, the expectation of designing investigations and analyzing the results is new. At home, they can be best supported by having conversations around their observations in lab and how these observations can support a claim. Ask questions that attempt to deepen their understanding. It’s OK if you don’t know the answer – just listen and keep asking questions. My hope is that students shift to longer explanations that use their evidence. Keep talking!

Again, I have really enjoyed getting to know your students and appreciate the enthusiasm and energy they bring to science class. It’s hard to believe that the month of August is at an end. As always if you have any comments or questions, do not hesitate to contact me. Please enjoy your weekend and try to spend some time outside looking for changes in the season!

Column Ecosystems and Yeast

Students are settling back into the routine and the class is humming along. I’m enjoying the shift from teaching a math / science rotation to solely science. At the same time, I realize how my reflection time and work on this blog has languished over the last year. I’m going to start with an attempt to review weekly activity and hopefully build upon this routine.

We’re about three weeks in and trying to juggle a couple of units at a time. As the school transitions to the NGSS, shifting of units between grade levels has taken place. Holes in the curriculum were also identified and new units placed on the docket for the year. It is going to be a busy one! The immediate impact is that ecosystem concepts traditionally in 7th grade will move to 6th grade to take the place of cell form and function, which is heading to 7th. Wanting to at least expose students to both topics in this transition year, we’re double dipping our time. I would love to know how other schools are setting up the flow of units. We have chosen to move from large systems in 6th through a process year in 7th to the “tiny” interactions in 8th.

This week completed the creation and loading of bottle ecosystems.


Each ecosystem has three chambers: decomposition, terrestrial and aquatic. Once the bottles were constructed, my teaching partner and I set-up an “assembly” line in a main corridor to load each chamber. I was surprised at how quickly (and relatively cleanly!) students passed through the line. The following class, baseline measurements of water quality, organism counts and layers descriptions were made.

With the ecosystems looking out of the window, we continued with an earlier conversation regarding the characteristics of live. Beginning with the claim that yeast is a living organism, students are being asked to collect evidence to either support or refute the claim. I have the feeling that the concept of collecting evidence is a new one for most of these budding scientists. As a first lab, it is highly structured to provide a model for students though we will soon begin dropping much of the scaffolding as students begin designing their own investigations.

IMG_0155Students measured amounts of yeast and sugar, added warm water and topped the flask off with a balloon. After ten minutes of observation, we regrouped for a quick discussion to link our evidence with the characteristics of living things. The “grand finale” was to send the captured gas through a straw into a test tube of Btb solution with the hope of a color change. As a whole, classes had about a 50% success rate on the final step.

Where do we go from here? More evidence is needed in order to say that the yeast is living or not. Moving into a discussion of variables, students will modify the experiment to search for a response to stimuli. We’ll pull out the microscopes to look at cells and try to link an increased rate of gas production to yeast reproduction. During each step, I hope to slowly pull back as students become familiar with investigations.