Teacher Addition
7th Grade Module 1:
Best Bread Company
A bread company wants to find the best way to make bread using yeast.
Your class is in competition with other 7th grade classes to find the best
approach by November 14th (Friday). Your challenge is to present the
best approach and have it tested: the winning class gets free pizza!
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Outline
Day 1) Introducing SciTrek and the Yeast Module.
During this lecture, the instructor should give a brief review of metabolism; covering the mass balance equation for glucose to
CO2 metabolism. This will setup a good platform for what the module will be measuring (CO 2 production). Also it is a good time
to talk about the difference between prokaryotes and eukaryotes. If possible talk about organelles/lack of them, and the overall
size difference. The volume of an E. coli cell is 1µm3 while the volume of Saccharomyces cerevisiae is 50 µm3.
Yeast (oval) E coli (rod)
Human Cells
E. coli Contamination
After recapping metabolism emphasizing the products of respiration and a little microbiology, you should perform the respiration demo. Before the period starts add at least 25 drops of phenolphthalein solution to 50-100ml of ddH2O pH 7.0. The
solution should be a blue color. Ask the students what you exhale, and then using a straw blow bubbles into the flask ( It should
change from Blue to clear to yellow) The solution changes color based on pH, but telling the students that it is due to CO2
production is fine. Next set up the yeast demo. Three things will be constant for every experiment they preform 1) Time (10
min), 2) amount of yeast (provided as 3 gram tubes) 3) volume (every reaction has to be 100 mL). Heat water to 28-30 C,
added 3 packets of sugar, added the yeast and the top of the apparatus. Stir contents every few minutes. During this time the
students should be recording observations of the system and constants. The first experiments that the students attempt will be to
reproduce the control. This will provide an excellent opportunity to gather enough data to introduce statistical error, precision,
accuracy, outlies if available.
Day 2) They will perform in class literature searches. This is an important skill to acquire and is one all scientist use on a daily
basis. Ideally you should have them stay in there groups and first brainstorm what variables they recorded on the previous day
that can contribute to CO2 production. It is also helpful to first explain how to search complex ideas using google/ general search
engine. Do not type sentences, isolate the key words and the principle and start small and build up the quarry. The goal of this
day is for the students to find other material that leads to the best conditions for yeast to grow. A secondary goal is to explain
when it is appropriate to trust information found on the internet. What areas have the most trust worthy reputations? A good time
to have this conversation is either close to the end or at the beginning of the next class, when multiple groups have a chance to
find similar information, for the purpose of comparing the results.
Day 3) The class will perform the control experiment today. Before they start it would be best to talk about what they discovered
on the previous day and have short class discussion.
Day 4) The groups can begin to explore and experiment, most likely only doing two experiments.
The learning goals for the 7th grade SciTrek program, involving two modules are:
1. For the students to acquire the content knowledge related to micro-organisms which are
specified in the relevant documents (e.g., Next Generation Science Standards).
2. Students be able to distinguish:
a. Between an observation and an inference
b. A question which is testable by experimentation and one that is not.
c. An experiment suitably designed to address a testable question and one which is not.
3. Be able to calculate the mean of a set of numbers and be able to:
a. Identify outliers and their potential causes
b. Distinguish and evaluate between sets of data which have different levels of
variability.
Notes in red are only on the teacher handout. And are meant to give possible answers to what the students could find/ think of.
VOCABULARY
Science: The study of the material world using human reason. The scientific method is the way
humans reason and apply logic to data to help us gain knowledge of the world.
Scientific Practices: A series of activities that scientists participate in to both understand the
world around them and to communicate their results with others. (The specific practice worked
on in this module is identifying correct conclusions.)
Observation: A description of the item of interest. This could include contents, mass, size, color,
temperature, smell, texture …
Inference: An interpretation or judgment based on knowledge from past experience. Something
you think is likely based on what you observe.
Testable Question: Something for which an experiment can be designed to answer.
Non-Testable Question: Something for which an experiment cannot be designed to answer the
question. For example questions involving opinions, things that cannot be measured, or words
that are not well defined.
Prediction: What you expect to happen based off of previous measurements/observations.
Results: The data recorded from an experiment.
Controls: The variables that are not changed in an experiment.
Experimental Set-Up: The materials, changing variable, and controls that are needed for an
experiment.
Experiment: A test or trial to discover something unknown.
Procedure: A set of steps to determine the answer to a question.
Changing Variable: The variable that is changed an experiment.
Data: Evidence collected from experiment(s) (measurements or observations), the second part of
a conclusion.
Conclusion: A claim supported by data.
Experimental Setup/ Demonstration
YEAST CO2 EXPERIMENT
OBSERVATIONS
Observations are characteristics about the experiment or system you are studying. For example in
the experiment how did the scientist measure the CO2 produced? Note: yeast amount and
liquid amount will be kept constant throughout.
The CO2 Displaces water from the central flask into the graduated cylinder. ~1 cm3 gas =1
mL
What other observations about the experiment can you make: (List 3). For example:
1. Speed of the flask swirling.
2. Size and type of flask. Connections made to flasks, tubing, and placement of
connections.
3. Temperature.
4. Type and amount of material added to flask (yeast, sugar).
Variables
Predictions help guide scientist to create an experiment, and help with overall understanding.
Think about what variables (features you think might be important) are in the experiment and
make predictions of what will change if the variable is changed. Try to predict changes you
can measure.
Variables are parameters that can be changed and cause a different effect from the control.
What do you think might be contributing to CO2 production?
Variable
How will the Variable effect CO2 Production
This will increase CO2 produced, so long as it's not above 110 F
Temperature
The media that the yeast grows in, adding too much sugar will
actually lead to less CO2 production.
Sugars
Water, soda, juices, milk...
Liquids
Speed of flask movement will change the ratio of oxygen in the
system. Frequency of flask movement.
Flask swirling
Day 3) 11-5-14
Outside Research
Today you will be looking for the best conditions for yeast to produce CO2. Science is not just
about designing experiments and collecting data. First we have to be well informed about what is
known on the topic you are investigating. This is called “looking at the literature” because you
are finding what other people have discovered. What is one way you know of doing this? You
guessed it: the Internet!! The yeast in the experiment is Saccharomyces cerevisiae, which is the
taxonomical genus and species. What does this Latin name translate to? sugar fungus of beer
Example Searches:
What temperature is the human body at? 98F
Now you should begin looking for information about Saccharomyces cerevisiae.
First brainstorm what factors would affect CO2
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What websites did you fine? List at least four
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Do you trust the information they provided?_____________________
Why or why not?
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Day 3) 11-5-14
What factors did you Search and what result did you find.
Factors for CO2 Production
Website Results:
Temperature
37C is best, above 40C kills
Sugar
What type is the best? Possible inquire
question to ask the students?
Day 3) 11-5-14
Experimental Considerations
1. You must make measurements because you will make a bar graph of your data.
2. You are required to keep the following constant: amount of yeast, time for CO2 production 10
min for gas collection, size of containers and tubing.
Changing Variable(s)
You will get to perform two experiments each day. For your first experiment decide which
variable(s) (they can change 1 variable per experiment) that you would like to test. Having
students design “poor” experiments, for example by changing two or more variables, is OK
if they can learn from these, so be careful not to over-coach. For each changing variable that
you select state why you think that variable will affect CO2 production.
Changing Variable1:_______________________________________
Why do you think changing variable 1 will affect the amount of CO2 production?
______________________________________________________________________________
Changing Variable 2:_______________________________________
Why do you think changing variable 2 will affect the amount of CO2 production?
Question
Question our group will investigate:
If we change
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what will happen to
__________________________________________________________________?
Control Experiment
Every group will be perform the same experiment to establish a baseline, so that your class as a
whole can see if the variable changed increased or decreased the amount of CO2 produced.
Experimental set up:
1) Set up the apparatus.
2) Get heated water (27C)
3)Dissolve the sugar (3 packets)
4) Start the experiment and collect CO2 for 10 min.
Class Data:
Group
1
2
3
4
5
CO2
Produced
Class Average:__________________ Are there outliers:_________________________
6
7
Day 3) 11-5-14
Experimental Procedure
For each experiment you perform record the exact process you used. Make detailed notes of the
conditions that are the same.
Experiment 1) Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
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Day 3
CO2 Produced
100
90
80
70
60
50
40
30
20
10
0
1
Exp
Day 4) 11-6-14
Experimental Procedure
For each experiment you perform record the exact process you used. Make detailed notes of the
conditions that are the same.
Experiment 1) Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
______________________________________________________________________________
______________________________________________________________________________
Experiment 2) Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
______________________________________________________________________________
Results
CO2 Produced
100
90
80
70
60
50
40
30
20
10
0
1
Exp
Day 4
Day 5) 11-7-14
Experimental Procedure
For each experiment you perform record the exact process you used. Make detailed notes of the
conditions that are the same.
Experiment 1) Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
______________________________________________________________________________
______________________________________________________________________________
Protocol:______________________________________________________________________
_
______________________________________________________________________________
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Results
100
90
80
CO2 Produced
70
60
50
40
30
20
10
0
1
Exp
Day 5
Day 7) 11-10-14
Experimental Procedure
For each experiment you perform record the exact process you used. Make detailed notes of the
conditions that are the same.
Class Experiment Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
______________________________________________________________________________
______________________________________________________________________________
CO2 Produced
Class Duplicate Experiment
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
0
1
2
Replicates
Trial 1 Results)_________________
Trial 2 Results)_________________
Average:______________________
3
Day 7) 11-10-14
Experimental Procedure
For each experiment you perform record the exact process you used. Make detailed notes of the
conditions that are the same.
Class Experiment Variable changing:___________________________________!
Protocol:______________________________________________________________________
_
______________________________________________________________________________
______________________________________________________________________________
CO2 Produced
Class Duplicate Experiment
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
0
1
2
Replicates
Trial 1 Results)_________________
Trial 2 Results)_________________
Average:______________________
3
Day 9) 11-13-14
Project Title:
___________________________________________________________________________
Authors (group members):
______________________________________________________________________________
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Protocol
This is the protocol your class agrees will produce the most CO2. The entire class will follow this
protocol exactly. We will take the average of all the group’s results and determine how much
variation there is. This process is called taking replicates, which is an important part of doing
science. Why? The values of CO2 produced from each group will be averaged and compared to
the other classes.
Step by Step Instructions:
1.
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2.
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3.
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4.
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5.
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6.
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Day 9) 11-13-14
Class Results
Team
Volume of CO2
Produced
1
2
3
4
5
Average CO2 Produced:________________
Are there outliers:
______________________________________________________________________________
Class Data Set
5
Te
a
m
4
Te
a
m
3
Te
a
m
2
m
Te
a
Te
a
m
1
120
110
100
90
80
70
60
50
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20
10
0
Day 10) 11-14-14
Now we will make conclusions from the data you collected in your experiment:
How many variables did you change in your experiment?___________________________
Can you make a conclusion from your data? YES____ NO______
If NO, why?
______________________________________________________________________________
____________________
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____________________
If YES, we can conclude:
Conclusion:____________________________________________________________________
_________________
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because,
Claim:________________________________________________________________________
___________________
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If you could re-do this experiment what would you do differently?
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Activity #1: Environmental influence on organism growth
Day 10) 11-14-14
What Environmental Factors did you change in your experiment (Ex/ temperature, amount of
sugar) and what were the effects on the yeast (More/less yeast growth)?
Is there a temperature for growing yeast that produces the most CO2?
A Scientific Explanation consists of a claim, evidence, and conclusion.
Write a scientific explanation for why the yeast grew better or worse at certain temperatures? For
example:
Claim: Exercising every day makes you healthier.
Evidence: People who exercise regularly have fewer health problems and live longer.
Conclusion: Exercising leads to improved health and a longer life.
What to expect each day, and what we are trying to get across.
Day 4 This day: The groups will decide on variables to explore. You do not have to lead the
students to what you think is the correct variable ( in fact don’t). We expect that this day will be
less productive in the since that the students will not generate data. But the main point is for
them to work out experimental design... changing one variable at a time and asking what will
happen.
Day 5 This day: The class will talk about what they did on the previous day. One member from
each group will come up and show the graph with their group’s data (This will alternate between
members for each day). The broad goal for this day is for the class to talk about data presenting
and to show the data in a way that is clear. Also on this day: Discussion about statistical home
work from when they do it.
Day 6 This day: The discussion will lead into what parameters they believe is affecting CO2
production. The goal is to have at least two clean experiments. Voluntaries are encouraged to
engage students with questions that they think might lead the group to a more conclusive result
but without biasing the group direction. Example: One experiment had coca cola as the media
and the second had sugar and water. The volunteer could ask the group what they think is in the
coca cola that made it produce more CO2 then the sugar water. Obvious answer is that the coca
cola had significantly more sugar in it then what was available in the sugar water experiment
(Note: any soft drinks the kids ask for will be decarbinated). These kinds of question can help a
stumped group.
HW2: The class will be given a short HW assignment which will guide them to looking at their
data (group specific) generated from Wed-Fri and figure out what parameters they test produced
the most carbon dioxide.
Day 7 This day: The fourth person from each group will go to the front of the class and state
what experiment they found produced the most carbon dioxide from the hw. We expect to see
several (3-5) parameters after everyone presents. From these results the class lead by the teacher
Day 10) 11-14-14
will decided what variables they want to evaluate (like 2) then the class will split in half and two
groups will look at the same variable and act as replicates.
Day 8 This day: At the beginning of class each group will present the data from Monday and the
class will go over the topics of duplicates and outliers. From here the class will decided what
parameters they would like to evaluate further. Perhaps one of the same from Monday or
possible a new one.
Day 9 This day: The class will decided what protocol they will follow after evaluating the data
generated from Mon and Wed. Each group will perform as many replicates of the Master
protocol as they can.
Day 10 This day: The class will be led in a discussion about data analysis and outliers with the
class data. If time is permitted we will go over more subject material about microorganisms.