Stretchy Worms (Teacher Copy)
Florida Sunshine State Standards Benchmark: SC.H.1.3.5 AA
The student knows that a change in one or more variables may alter the outcome of an
investigation.
Objective: SC.H.1.3.5
I can explain how changing a variable in a science experiment will change the results.
Background Knowledge:
Scientists use experiments to search for explanations to their questions. They design
experiments and control certain aspects of them. In the experiment they have the
ability to change certain things while keeping other things constant.
The parts of an experiment that can change are called variables. A variable is any
factor, trait, or condition that can exist in differing amounts or types. An experiment
usually has three kinds of variables: independent, dependent, and controlled.
The independent variable is the one that is intentionally changed by the scientist. To
ensure a fair test, a good experiment has only one independent variable. As the
scientist changes the independent variable, he or she observes what happens.
The scientist then focuses his or her observations on the result of the independent
variable, which is the dependent variable, to see how it responds to the change
made to the independent variable. The new value of the dependent variable is caused
by and depends on the value of the independent variable.
For example, if you open a faucet (the independent variable), the quantity of flowing
water (dependent variable) changes in response to how much you turn the faucet--you
observe that the water flow increases. The number of dependent variables in an
experiment varies, but there is often more than one.
Experiments also have controlled “variables” or constants. Constants are
conditions or other aspects of the experiment that the scientist must keep constant.
The scientist must observe them carefully. For example, if we want to measure how
much water flow increases when we open a faucet, it is important to make sure that
the water pressure (the controlled variable) is held constant. (We can run the faucet for
a time period to observe changes in pressure.) Both the water pressure and the
opening of a faucet have an impact on how much water flows. If we change both of
them at the same time, we can't be sure how much of the change in water flow is due
to the faucet opening and how much is because of the water pressure. It would not be
a fair test. Most experiments have more than one controlled variable.
In a good experiment, the scientist must be able to measure the values for each
variable. Weight or mass is an example of a variable that is very easy to measure.
Engage:
Give each group a Gummy Worm and ask students to identify or list three different
characteristics about the worm. As a whole group, list the observations made by the
class. Guide students to identify the fact that the Gummy Worm is elastic and can
stretch. Explain to the students that you want to find out if the elasticity of the worm is
proportionate to the amount of mass it can hold. Ask the students about variables that
could affect elasticity. Guide the students to discuss temperature. If needed, discuss
molecular movement at different temperatures. Instruct students to write a hypothesis
statement (if…then statement).
Problem Statement: How does temperature affect the elasticity of a Gummy Worm?
Hypothesis:
If (independent variable),
then (dependent variable)
Materials:
 9 Gummy Worms
 pencils
 paper rulers – downloadable from
http://www.vendian.org/mncharity/d
ir3/paper_rulers/UnstableURL/rules_
cm.pdf


thermometers
scissors







clear tape
triple beam balance
sandwich bags
large paperclips
masses – washers or pan balance
masses
lab sheets
graph paper
Teacher Prep:
1. Place 3 Gummy Worms per group in a sandwich bag and let sit in a cooler with
ice.
2. Place 3 Gummy Worms per group in a sandwich bag and let sit in the classroom
until they are at room temperature.
3. Heat a pot of water on low temperature. Place 3 Gummy Worms per group in a
sandwich bag. Place the bags in a water bath. (Monitor temperature to not boil
or melt bags and Gummy Worms. The purpose of the water bath is to slightly
warm the Gummy Worms.)
Explore:
Procedures : Direct students to carry out the following procedures:
1.
2.
3.
4.
5.
6.
Identify room temperature and record on your data sheet.
Take a room temperature Gummy Worm out of the bag.
Tape the paper ruler to the area where the worm will be hanging.
Attach a paperclip to one end of the worm.
Attach a sandwich bag to the end of the paperclip.
Tape the empty end of the Gummy Worm to a table so that the worm and
sandwich bag hang next to or in front of the paper ruler.
7. Measure your worm by placing a mark on the paper measure.
8. Add mass to the sandwich bag and mark the length of the worm. Continue to
add mass and mark the length until the weight of the bag tears the worm.
9. Find the mass of the sandwich bag and record.
10. Repeat steps 2-9 with the other 2 worms from the same bag.
11. Measure the temperature of the cooler. Record on your record sheet.
12. Complete steps 2-10 utilizing the cold Gummy Worms.
13. Measure the temperature of the heated water. Record this on your record sheet.
14. Complete steps 2-10 utilizing the heated Gummy Worms.
15. Graph the results by creating a bar graph. Use red, blue and black to depict
warm, cold and room temperature worms.
Explain:
The focus of this lesson is to recognize that by changing a variable, scientists can alter
the outcome of an experiment. Walk around to each group and ask the students to
identify the independent variable (temperature of the Gummy Worms) and the
dependent variable (mass of the bag when the worm tears) in the science experiment.
Have the students identify the controlled variables (constants). Ask the students to
think of other independent variables they could test that would alter the outcome of the
experiment.
Elaborate:
As a whole class, compile the data from several groups and compare and contrast each
group’s results. Discuss why there were differences among the groups. Discuss the
importance of controlled variables (constants) and precise replication in forming correct
conclusions.
Evaluate:
Use the following to evaluate this lab: the lab sheet with collected data, graph, and the
conclusion (see below for recommended components to a lab conclusion).
Ask the students to journal in their science notebook a response for the following
questions:
1. What possible explanations can you offer for your findings?
a) Evaluate your method.
b) State any assumptions that were made which may affect the result.
2. What recommendations do you have for further study and for improving the
experiment?
a) Comment on the limitations of the method chosen.
b) Suggest how the method chosen could be improved to obtain more
accurate and reliable results.
3. What are some possible applications of the experiment?
4. How can this experiment or the findings of this experiment be used in the real
world for the benefit of society?
Scientist: _______________________________ Date: ____________ Period: ______
Stretchy Worms (Student Copy)
Objective: SC.H.1.3.5
I can explain how changing a variable in a science experiment will change the results.
Background Knowledge:
Scientists use experiments to search for explanations to their questions. They design
experiments and control certain aspects of them. In the experiment they have the
ability to change certain things while keeping other things constant.
The parts of an experiment that can change are called variables. A variable is any
factor, trait, or condition that can exist in differing amounts or types. An experiment
usually has three kinds of variables: independent, dependent, and controlled.
The independent variable is the one that is intentionally changed by the scientist. To
ensure a fair test, a good experiment has only one independent variable. As the
scientist changes the independent variable, he or she observes what happens.
The scientist then focuses his or her observations on the result of the independent
variable, which is the dependent variable, to see how it responds to the change
made to the independent variable. The new value of the dependent variable is caused
by and depends on the value of the independent variable.
For example, if you open a faucet (the independent variable), the quantity of flowing
water (dependent variable) changes in response to how much you turn the faucet--you
observe that the water flow increases. The number of dependent variables in an
experiment varies, but there is often more than one.
Experiments also have controlled “variables” or constants. Constants are
conditions or other aspects of the experiment that the scientist must keep constant.
The scientist must observe them carefully. For example, if we want to measure how
much water flow increases when we open a faucet, it is important to make sure that
the water pressure (the controlled variable) is held constant. (We can run the faucet for
a time period to observe changes in pressure.) Both the water pressure and the
opening of a faucet have an impact on how much water flows. If we change both of
them at the same time, we can't be sure how much of the change in water flow is due
to the faucet opening and how much is because of the water pressure. It would not be
a fair test. Most experiments have more than one controlled variable.
In a good experiment, the scientist must be able to measure the values for each
variable. Weight or mass is an example of a variable that is very easy to measure..
Problem Statement:
How does temperature affect the elasticity of a Gummy Worm?
Hypothesis:
If (independent variable),
then (dependent variable)
Materials:













3 room temperature Gummy
Worms
3 cold Gummy Worms
3 heated Gummy Worms
pencils
paper rulers
scissors
clear tape
triple beam balance
sandwich bags
large paperclips
Masses – washers or pan balance
masses
lab sheets
graph paper
Procedures:
1.
2.
3.
4.
5.
6.
Identify room temperature and record on your data sheet.
Take a room temperature Gummy Worm out of the bag.
Tape the paper ruler to the area where the worm will be hanging.
Attach a paperclip to one end of the worm.
Attach a sandwich bag to the end of the paperclip.
Tape the empty end of the Gummy Worm to a table so that the worm and
sandwich bag hang next to or in front of the paper ruler.
7. Measure your worm by placing a mark on the paper measure.
8. Add mass to the sandwich bag and mark the length of the worm. Continue to
add mass and mark the length until the weight of the bag tears the worm.
9. Find the mass of the sandwich bag and record.
10. Repeat steps 2-9 with the other 2 worms from the same bag.
11. Measure the temperature of the cooler. Record on your record sheet.
12. Complete steps 2-10 utilizing the cold Gummy Worms.
13. Measure the temperature of the heated water. Record this on your record
sheet.
14. Complete steps 2-10 utilizing the heated Gummy Worms.
15. Graph the results by creating a bar graph. Use red, blue and black to depict
warm, cold and room temperature worms.
Data and Observations:
See Data Sheets on upcoming pages.
Beginning
Length in
cm
Mass of
bags in
grams
Worm
1
Room Temperature
Worm
3
_____________C
Worm
2
Average
Worm
1
Cold Worm
Worm
3
Average
________________C
Worm
2
Worm
1
Heated Worm
Worm
3
Average
_____________C
Worm
2
Evaluate:
Part A: Review your data table and create a bar graph that shows the relationship
between the temperature of the worm and the mass of the bag when the worm tears.
Don’t forget to use the data from all three trials and your average. Remember that the
independent variable should be on the x-axis and the dependent variable should be on
the y-axis. (12 bars total)
Mass of the
bag in grams
Temperature of the worm
in C
Part B: Complete journal assignment given by your teacher in your science notebook.