Original Lab:
Revised Lab:
Endothermic and Exothermic Reactions
We have discussed five signs that we can observe to determine if a chemical reaction has
occurred. Today we are looking at one of those five signs: temperature change. Earlier in the
unit we discussed endothermic and exothermic reactions; endothermic reactions have heat
entering and exothermic reactions have heat exiting.
You must wear gloves and safety goggles throughout the entire lab!!!!!
Part One: Creating a Procedure
Your job is to investigate at least six combinations of chemicals that are provided. There is a
group of chemicals labeled A and a group labeled B. You can combine any item in A with any
item in B. You need to make 6 different combinations.
Group A
Group B
Epsom Salt
Water
Vinegar
Hydrogen
Peroxide
Bleach
Baking Soda
Ice
Calcium Chloride
Dry Yeast
Sodium Sulfite
Create a table below to show the different combinations of chemicals you will use:
Below you will find a list of materials that will be available to you to explore temperature
change.
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Beakers
Thermometers
All chemicals listed above
Stirring Rods
Stop Watch
On the lines below write a detailed procedure that your lab group will use to test the
temperature change in each combination of chemicals (chemical reaction).
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Stop Here! Miss Kramer must approve your lab procedure 
Pluses:
Arrows:
Use the information given from Miss Kramer to make revisions to your procedure. Show her
your edited procedure. One you have her initials in the space below you can begin your
investigation.
Part Two: Data Collection
An empty table has been provided to help you collect your data as you investigate temperature
change in a chemical reaction. Fill in the necessary information. If there is data you are
collecting that the table does not have, just add in a column or row.
Combination of
chemicals
Initial Temperature
Final Temperature
Endo or Exo or No
Rxn?
In the space below, draw an example of the setup you are using in your investigation. Be sure
to label the different materials that you are using.
Part Three: Analysis
1. Based on your results, define exothermic in your own words. Provide two examples of
an exothermic reaction that you tested.
2. Based on your results, define endothermic in your own words. Provide two examples of
an endothermic reaction that you tested.
3. What were some possible sources of error during the lab?
4. Based on the error you discussed above, what are some revisions you would make if you
did the lab again?
5. Describe how temperature change can be used in determining whether a chemical
reaction has occurred. Use the words endothermic, exothermic, and temperature
change in your response.
After reading Colburn’s piece about making lab activities more open ended, I was inspired to
alter pieces of a lab that I had done in my first placement. In the original lab, the procedure was
written step-by-step so that the students could simply follow the steps and use the labeled
materials in the basket. The last step in the procedure also guided students in how to fill in the
data table to determine the change in temperature for the given reaction. In the original lab,
the combination of reactions were predetermined and the students only had to mix the
chemicals and record the results. In retrospect, the lab was the epitome of a “cookbook lab”.
Colburn, along with the other readings from the previous class, provided some excellent
suggestions about how teachers can alter labs to make them more inquiry-based. I decided to
use an example that Colburn provided in his reading. Colburn discussed that removing pieces of
the procedure or the data table places an increased sense of ownership over the lab activity. I
like the idea of seeing data recorded in different forms but for this lab I thought removing the
procedure would be a better fit.
After removing the procedure from the lab I found that it could provide an excellent
opportunity for scaffolded revision of a lab procedure. In the revised lab, I gave a direction to
write a procedure using the given information and after it has been written, the students need
to have the procedure approved. Students who are already successful in writing appropriate
laboratory procedures will get the okay and they can begin the investigation. Students who are
still developing their procedure writing skills will have a low-risk opportunity to revise and edit
their laboratory procedure. I will provide them with plusses and arrows on their original lab
procedure; the students will then take those arrows to make revisions. This can be a powerful
process in that it can help students see why detail and organization is important in science. I
think another way revision can be implemented into the lab could be after an entire lab activity
has taken place. I love introducing the fact that science is messy. Students could create a
procedure, run the lab, and acquire results only to find out that they changed too many
variables and their results are invalid. The next class period could be an opportunity to make
changes to the procedure to improve their results.
In the revised lab, I decided to group the chemicals but allow the students to choose the
combinations. This will result in unique experiments in which all groups do not have to test the
same combinations. This can lend itself to a post-lab discussion in which groups compare
results and discuss which combinations were exothermic and endothermic whether or not they
tested that combination. For the revised lab, I gave a list of the materials that were used in the
original lab but I did not explicitly write out how to use the tools. Students are required to write
down how they would use the tools in their procedure; this can also result in unique
experiments and procedures that would be a rich and powerful post-lab discussion.
I decided to keep the data table in the lab because it is important for me that the students
interpret what endothermic and exothermic actually mean in terms of data. Writing the data
and being faced with the question if the reaction was endothermic or exothermic requires the
students to build on their prior knowledge. A quick glance over the data table during the lab
can show me if the students understand the difference between endothermic and exothermic.
I kept the analysis questions from the original lab that I felt were open-ended and important to
this specific lab. I added in a question about error and revision to demonstrate that revising a
procedure one time is usually not enough in science. This can begin a discussion about science
being messy and how procedures and theories continually change in science. I also added the
final analysis question that functions as a summary for the day. The students will work in lab
partners or small groups during the data collection but the analysis will take place
independently. The final summary question will be used to assess whether the individual
students understand temperature change with regard to endothermic and exothermic.
The revised lab is something I envisioned to happen during the middle of the school year.
Procedure writing is not a skill that students should be expected to do on the first day of school.
I think it is important to scaffold the steps included in writing a procedure. The more these skills
are practiced in the classroom, the less intimidating a lab will be that requires a procedure to be
written. Independently writing a procedure and organizing and collecting data are important
skills in an inquiry-based lab experience. I plan to have students practice these skills
consistently in the classroom.
References
Colburn, Alan. (1997) How to make lab activities more open ended .CSTAJournal, 4-6.