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.

IMG_0177 IMG_0178



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.


Inquiry: The Yearlong Experience

This video was one of the final group projects turned in. Simply put, I asked students to tell the story of their project and do it in a way that would engage the audience. This group even put in a bonus song halfway through the presentation that captured the overall idea of their work.

This ends another year of inquiry. Personally, I set goals for myself that I didn’t keep. One of the goals was to write more about the process. I got started; writing at the beginning as students decided on their questions but then I got side-tracked. The overall picture is that students began the first few days of the school year walking through campus, wondering and questioning. Groups were formed based on interest and students then prepared background information reports, hypotheses, and procedures. By September, most groups began collecting data and this repeated for the rest of the year. Approximately once a month, the class would scatter as students logged in a new data point. In May, we began wrapping up the project and discussing results. Students individually created a report and as a group prepared a presentation.

Will I continue this next year? If I was staying at my current job, the answer would be a resounding “Yes!” Each year of this project reinforces the idea that need the opportunity to work on perseverance. How many times is a lab performed where students collect data and move on? They miss the chance to retool ideas, to improve technique and to return time after time to the same idea. Here are a few thoughts provided by students in their final reflection:

When asked the benefit of a year-long project:

  • The question can have more data points which shows a wider range and there is more time focused on one project. It can also show how effective in the manipulated variable of time.
  • We had the privilege to go out in the field to a location of our choosing and learn what we wanted at our own leaning pace.
  • In this year, we have all improved a lot. We have learned how to have great conversations with group members, team-building and responsibilities.
  • At first, some of us wanted to do some things alone; however, it does not work out well. We needed to hep each other to get everything done.
  • It is extremely important in a year long project to organize your data and develop strong observation skills.
  • The project taught me a lot of things on team-building, responsibilities and time managing.
  • I learned a lot from this inquiry project, from how to collect samples and other lab techniques to how to organize data and analyze it and then present to others. It gave me a good idea of how to do a good experiment and what experiment is like.

  • After a year, I have learned not only how to test starch; the process of how to do an experiment became my valuable property.
  • I learned to overcome difficulties without having an emotional breakdown.

A few student “surprises”/”enjoyments”:

  • I was definitely surprised about how complicated to start an experiment.
  • At the start, I thought this project was going to be a burden on my shoulder, however after having fun in every field day with other members of the group, I fell in love with this project.
  • I enjoyed how we got to have fun times and serious times doing this project. We had some days we are just so busy, it was not fun but there are days we get to have fun and relax at the pond with the good weather.

  • I really enjoyed when the other group members were there, we were exploring around the pond like scientists.
  • I personally dream to become a mad scientist so practicing experiment skills is very important to me.

Mixing Hot and Cold


Students came into my class to see the comic above projected on the screen. The comic reminds me of frustrations at my grandmother’s house trying to get the temperature just right. A slight adjustment would either freeze or scald me. My students looked with blank expressions. It seems as if none of them have this experience. Given the homes of many, I wonder if they simply program in the water temperature of choice. What are they missing from this daily experiment?

With the comic intro a flop, I asked each to individually answer the following:

  • Water at two temperatures are mixed together. The two temperatures are 50 C and 10 C. Please make a selection that best fits what you believe will happen to the temperature once they are mixed.
  1. The temperature of the “colder” water will be subtracted from the “warmer” water, resulting in a final water temperature of 40 C.
  2. The temperatures of the two waters will be averaged, resulting in a final temperature of 30 C.
  3. The temperatures of the two will be added, resulting in a final temperature of 60 C.

Source Article: Teaching about Heat and Temperature Using an Investigative Demonstration, Science Scope , December 2011

Students were also asked to explain why they chose the subtraction, average or addition conception. In my class of 20 students, an even selection was made with 10 students selecting subtraction and 10 selecting average. For me, the line was almost predictable. Before class, I put students in groups that I anticipated would have similar conceptions. That way students would share initial ideas as they then moved forward and planned an investigation. My predictions were almost spot on. 

For me, the interesting information was found in the explanations of reasoning. Support for the subtraction conception:

  • I believe (a) because when cold hits something hotter it mixes together.Then the cold changes to warm because it mixes with the hot.
  • a, because there are more heat molecules than cool molecules and they will end up subtracting each other.
  • I chose “a” because I had mixed hot and cold water before and the temperature dropped.
  • A. The hot water is too hot that it will break those coldness in cold water. That the water temperature would stay at a higher temperature.
  • I believe that it is “A” because I made it into real life. When the two waters are mixed, the water is hotter but there is cold water which ends up having a hot water, but it’s colder than the original one.
  • A, because when the cold water meets the hot water the cold water is not going to become hot water. It is going to mix, so the temperature should become 40C.
  • You cannot add both of them up because they are like positive and negative numbers. Add more hot water and the water will be warmer.

Support for the average conception:

  • Because the energy of the hotter water would mix with the colder water and they will get averaged.
  • The water will cool down until both temperatured water becomes the same temperature.
  • Because the hot water will heat the cold water up and the cold water will cool the hot water down until they have the same temperature.
  • There is more energy in the hot water than the cold water. When the hot & cold water mix, the energy evens out so the temperature will be averaged.
  • B, because I believe the two waters are the same volume (mass) and the temperatures would come together and be divided by 2.
  • The temperature of the two waters will be averaged if the amount of water on both sides are the same. Temperature is a unit to show an amount of energy. If two energies get mixed, the temperature we get will be their average.
  • I chose “b” because the two cups of water contains the same amount of water mixed together. After the two cups of water mix together the temperature would be mixed and averaged.
  • Assuming that both are the same amount, the water mixed would result in 30C. Heat transfers quickly, the cold water drains the hot water’s heat while the hot water has cold temperatures spread through it. Both balance out each other.
  • I think the best choice is b because neither the cold water or hot water should be subtracted or added into each other so the best choice is to average both.
  • If the amount of both water is the same, the water will average out. The water is not “negative” or “positive”. There is a colder/hotter temperature for both waters so therefore they will average.

From this point, I asked students to grab a whiteboard to sketch, write a procedure and make a data collection table. The stumbling block on procedures was when to take the final  “mixed” temperature. In the end, each of the five groups produced data that supported the average conception.

Where now? Students made a prediction, planned an investigation and collected data. Next class involves making a claim, using evidence to support the claim, and reasoning to tie together their ideas. I’m looking forward to reading the students’ reasoning. They were given background reading that I hope will support the experimental data. Will I be treated with more insight into their thoughts on this concept?

Procedure Swap

“Write your procedure so that anyone in this class could follow it and collect data like you.” This was a common refrain of mine as students prepared procedures for various inquiry projects. I got a lot of head nods but some students seemed to quickly slap a few lines together and declare their procedure the best ever. Oh, the shock on their faces when we actually swapped procedures.

I did it over a two class period. The first day, one partner stayed with his/her project and the other moved on to perform the procedure of another group. The “owner” of the procedure read it out line by line for the newcomer to carry out. The catch was that only what was written could be read out loud. If something needed to be added or modified, it had to be done before the step could be completed. One pair finished immediately and a large smile was on the face of the boy who had performed the procedure.

“Finished already?”

“Yes, he told me to take out the plants, move one to the window and then clean up.”

“Did you collect any data?”

“Nope, it wasn’t in the procedure.” With those words, the other scientist simply shook his head. His group had left out many sections but the two returned to work and rounded out the procedure.

On the next day, I again switched up partners. However, this time no conversation was allowed. The “owner” of the procedure played the role of an observer and was expected to take notes on how the newcomer carried out the directions. At the end, the two sat down and discussed difficulties or places that were not completed as expected.

All in all, these two days were well worth it. Students worked with both written and verbal language skills – an important aspect with the ELL population in my classes. I enjoyed each debrief session with the students as they discussed what they liked about the procedures they performed and what could be improved upon.

The Question

In science, my 8th graders identified the topics of their year-long inquiry projects. There is a nice range of ideas including:

  • pH of rain  (Will this prove or disprove the Taiwanese myth regarding acid rain?)
  • amount of mosquitoes / biting midges on campus
  • water quality of the campus pond
  • soil quality of different campus locations
  • seasonal changes of trees
  • amounts of particulate matter in air throughout campus

The process of moving from a topic to a question challenged many students. In general, the questions were quite vague as students struggled with developing a relationship between variables. I attempted a round table discussion where a group presented its ideas and the other students provided items that they wondered about, but I don’t think that much of value was generated. My goal is to generate a culture of questioning and ownership with these projects and this will take time. We’re off to build background at the moment. Students have a bulletin board space outside the class for data and are building web pages. Over the next week or so groups will design procedures and I hope that they are collecting data by mid-September.