Biofuel and Bubbling Plants Grade 7 science Q 1
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Engineering Design Process Applied to Biofuel Production: Floating Plants
Goal: Increase the rate at which plants produce sugars so that these sugars can be used
to produce biofuels as an alternate to fossil fuels.
Problem: Design a system that increases the rate of photosynthesis in plants and the
quantity of sugars produced.
Research: Construct a system that will measure
the rate of photosynthesis, and conduct an
experiment to determine a baseline rate at
which that system produces oxygen (and
therefore sugars for biofuels).
Develop: Brainstorm a possible change to the
system that will increase the rate at which
photosynthesis occurs in plants.
Choose: Decide on a variable (color of light, and amount of sodium bicarbonate) that
your team will manipulate to attempt to increase the rate of photosynthesis.
Create: Construct the system you chose.
Test and Evaluate: Conduct an experiment to gather data on the rate of oxygen
production, using your system.
Communicate: Share your system with the class, why you chose the variable, and how it
affected the rate of oxygen production.
Redesign: Use class data to decide on the best design for a system that will produce a
maximum increase in photosynthesis.
Note: The Engineering Design Process (EDP) fits seamlessly with the 5-E model. For the purpose of focusing teachers and students on engineering, the EDP headings are used in this lesson.
Floating Leaves Grade 7 science Q 1 Lesson
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Engineering Design Challenge
Project Title: Biofuel Production: Floating Plants
Project Source: Exploring Life Community: http://tinyurl.com/y8uvnmb Video on Sinking Disks http://tinyurl.com/3lr6d3 (Brad Williamson, KABT) Floating Disk Assay http://tinyurl.com/6qnz5hv (Brad Williamson, KABT) Leaf Disk Assay http://tinyurl.com/7wxbbje (Carolina Biological)
Project Submitter: STEM Improvement Lesson Development Team
Grade Level/Subject: Science, Grade 7, 1st Quarter
Lesson Description: In this activity, students learn a simple technique for quantifying the amount of
photosynthesis that occurs in a given period of time, using a common plant – spinach. They experiment
with different colored lights and different concentrations of sodium bicarbonate solutions; then use this
information to design a system for increasing the rate of photosynthesis to be used in biofuels.
Engineering Challenge: Student teams are conducting research to help them write a funding request to
establish their own biofuel production firm. Teams first research how to measure the rate of
photosynthesis in a plant. They then design a system for increasing the rate of photosynthesis in the same
plants. This would increase the amount of sugars produced, providing a source of energy for biofuels.
After testing this system and comparing class data, they decide what way(s) of increasing photosynthesis
are most effective.
Educational Content Standards
MCPSS Engineering Standard:
2.1: Describe the steps of the engineering design process
Real World Connection: Engineering is the process used to design technology to meet human needs. For example, improved medical equipment or biofuels.
Floating Leaves Grade 7 science Q 1 Lesson
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MCPSS Mathematics to support this engineering challenge:
Collect and organize data.
Construct graphs to compare data and propose a best solution.
CC. Engineer solutions for real-life and mathematical problems involving centers of data.
ARMT+: Determine measures of central tendency (mean, median, and mode) and range using a
given set of data or graphs including histrograms, frequency tables, and stem-and-leaf plots. [CS-
12]
MCPSS Science to support this engineering challenge:
1.0 Describe characteristics common to living things, including growth and development,
reproduction, cellular organization, use of energy, exchange of gases, and response to the
environment.
12.0 Identify controls, variables and examples of hypotheses in a scientific investigation.
Learning Objectives:
Describe the steps of the engineering design process Conduct an experiment that provides indirect evidence that photosynthesis is occurring.
Use Centers of Data to make informed decisions and design a system that will increase the amount of sugar produced during photosynthesis to meet a real world problem.
Prerequisite knowledge:
Students should have some understanding of photosynthesis and the chemical reactions that take
place inside the leaf to produce sugars.
Students should understand how calculate and identify the mean, median, mode, and range of
sets of data.
Floating Leaves Grade 7 science Q 1 Lesson
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Materials required:
For each class provide:
2 sets of colored filters (or colored cellophane) – red, blue, green
1000 ml of 2% sodium bicarbonate solution
1 box of Sodium bicarbonate (baking soda)
Measuring spoons - ¼, ½, and 1 teaspoon sizes
Dishwashing liquid
Paper towels (a roll for each class)
500 index cards.
1 permanent marker (for teacher use only)
For each team of 3 students provide:
1 5-oz clear plastic cups
1 10mL syringe without needle
500 ml beaker
1 Clamp lamp with stand
Spinach – 2 leaves
1 one-hole punch
Coffee stirrer or craft stick
Clock with second hand, timer, or stopwatch
2 colored pencils or crayons – different bold colors
Materials provided for each team by the teacher:
• Aged tap water or distilled water – Approximately ½ liter of aged tap water per team (“Aged tap
Water” is water in an open container that has been allowed to sit for 36-48 hours to eliminate any
chlorine used in municipal water supplies. You may use distilled water if you prefer.).
• Spinach –1-2 healthy leaves per team
Teacher Preparation: Day 1
If you are using aged water, then approximately 3 days prior to the challenge, teachers should
prepare the water and set it aside. Or, you may use distilled water.
Watch this short video showing part of the procedure students will use in their lab.
http://tinyurl.com/7fyo924
Floating Leaves Grade 7 science Q 1 Lesson
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Make a set of Team Handouts for each team. These are in order in a single file for easy printing
that will require no collating. The pages are numbered so that students can easily keep them in
order. (FYI - the Team Handout file includes the following handouts: Experiment Procedures Day
1, Baseline Data Chart, Floating Leaves Data Graph, Baseline Data Analysis, Experiment
Procedures Day 2: Test Colored light, Experiment Procedures Day 2: Test Carbon Dioxide
Production; Single Variable Data Chart; Biofuel Production Design Proposal, Sugar Production Test
Chart, )
Place each set of handouts in a folder. You may paper clip the handouts together, but do not
staple them. (Be sure to make a set for yourself.)
Place a Team Folder (with the Team Handouts) in each team area.
Read the lesson, and be especially familiar with these handouts for Day 1: Experiment Procedures
Day 1, Baseline Data Chart, and Floating Leaves Data Graph. Prepare to help teams as they follow
these procedures.
Prepare the 0.2% sodium bicarbonate solution. Add ¼ tsp. of baking soda to 500 mL of distilled
or aged water. Add 1-2 drops of dishwashing liquid to this solution. (The detergent decreases the
surface tension, making it easier to infiltrate the leaf tissue with the solution so the leaf disks will
sink.) Have this solution available for the teams to use.
Set up the AV equipment and prepare to show the Floating Leaves PowerPoint.
Put a light (clamp lamp or other light) in each team area. Position the bulb about 12 inches from
the top of the table.
Prepare the following Materials Set for each team: In a container place a syringe, a plastic cup, a
one-hole punch, a coffee stirrer or craft stick, a stop watch or timer, 2 spinach leaves, and 2
colored pencils or crayons.
Make a Day 1 Collective Data Chart on the board on which teams can record the number of leaf
disks that rise to the top each minute. Keep the chart up all day so all teams in all classes can add
their data. You may use a chart similar to the diagram below.
(Be sure the squares are large enough
for each team to tally the number of
disks floating. Do not complete the
“Total Disks” row until the last class
period.)
Floating Leaves Grade 7 science Q 1 Lesson
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Teacher Preparation: Day 2
Set up the AV equipment and prepare to show the ppt.
Place each team’s folder in the correct team area.
Fill in a copy of the Baseline Data Analysis handout so that you can go over the correct
information with teams.
Place a Materials Set in each team area.
Have available the colored filters (red, blue, green), the aged (or distilled) water, measuring
spoons, dishwashing liquid, and baking soda.
Set up an area where team members can prepare their sodium bicarbonate solution. You will
need baking soda, aged or distilled water, measuring spoons, and liquid soap.
Prepare a Day 2 Collective Data Chart on which the teams can record the length of time it takes
all of the leaves to rise to the top for each variable (treatment). You may prepare the chart on
chart paper or create and project the chart via Smart Board or LCD projector/overhead.
Variable 1 min 2 min 3 min 4 min 5 min 6 min 7 min 8 min 9 min 10 min
Blue Light
Green Light
Red Light
4% Solution
8% Solution
16% Solution
(Student teams will tally the number of leaves that float at each minute. Be sure to leave enough space for all students to tally their data throughout the day.)
Teacher Preparation: Day 3
Set up the AV equipment and prepare to show the ppt.
Place each team’s folder in the correct team area.
Place a Materials Set in each team area.
Place an index card for each student in the team area.
Provide the colors of cellophane teams requested.
Set up an area where team members can prepare the sodium bicarbonate solution, as on Day 2.
Floating Leaves Grade 7 science Q 1 Lesson
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Prepare to project the Day 3 Class Data Table on the Smart board, or LCD projector/overhead; or
make a copy on chart paper or the board.
Team ID 1 min 2 min 3 min 4 min 5 min 6 min 7 min 8 min 9 min 10 min
TEAM ID #
TEAM ID #
TEAM ID #
TEAM ID #
TEAM ID #
TEAM ID #
(It is recommended that you make one chart for each class period. Or erase the data after each
class period and reuse the same electronic chart.)
Floating Leaves Grade 7 science Q 1 Lesson
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Floating Leaves Grade 7, Science, Quarter 1
Day 1
Engineering Connection: Engineering is the process used to design technology to meet human needs. For example, engineers may design improved medical equipment or improved methods for producing needed materials such as biofuels. Engineers often take advantage of the natural characteristics of plants to improve technologies and make our lives more comfortable. One way plants can be used is in the production of biofuels – a natural alternative to fossil fuels.
Introduce students to the project. Show Slide #1 as students arrive, and direct them to their
engineering teams.
INTRODUCE THE ENGINEERING DESIGN PROCESS (5 min.)
Tell students that today they will work together as student engineering teams. Explain
that engineering is about problem-solving. Engineers use the engineering design process,
shown on the slide and on the wall poster, to solve problems by creating new products,
systems, or other technologies. Say, "Let’s take a quick look at this process, and then we’ll
talk about each stage in more detail as we solve an engineering problem."
Show Slide #2 and point to the appropriate section of the diagram as you say:
First engineers must DEFINE THE PROBLEM.
Then they ask themselves some good questions about how they might go about solving
that problem and do some RESEARCH to gather the information they need.
Engineers use their research to DEVELOP different ideas and possible solutions.
After discussing the pros and cons of each idea, they then CHOOSE one of the possible
solutions to try.
Engineers CREATE the design, or system, they decided might solve the problem.
They TEST and EVALUATE this design.
Then they COMMUNICATE their results to one another and to others and ask more
questions. Should they REDESIGN their solution? If so, what might make it work better?
Notice that the REDESIGN stage does not have its own section. That’s because
Engineers often stop and redesign at any stage in the process. (Indicate the REDESIGN
arrow)
Floating Leaves Grade 7 science Q 1 Lesson
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DEFINE THE PROBLEM. (5 min)
Tell students we will now tackle the DEFINE THE PROBLEM stage. Show Slide #3 and
introduce students to the problem of fossil fuels.
Introduce students to the benefits of biofuels. Show Slide #4 and explain that biofuels
may have some downsides, but presently scientists and engineers think they are a better
choice than fossil fuels. They are interested in increasing production of biofuels.
• Explain the problem. Tell students that the Environmental Engineering Association is
asking our student engineering teams to help them solve a problem. Their goal is to
increase the rate at which plants produce sugars so that these sugars can be used to
produce biofuels. As student teams, they will research this problem and find a solution.
They then plan to ask the Environmental Engineering Association for funding to start their
own biofuel production firms.
Show Slide #5 and continue: The challenge, then, is to produce plant sugars at a more
rapid rate in order to increase the production of biofuels.
Ask students to think about the question in the callout balloon and ask if anyone has any
ideas for how we might do this.
RESEARCH (5 MIN)
• Lead students to recall photosynthesis information. Indicate the RESEARCH stage and
remind students that plants produce sugars through a process called photosynthesis. Show
Slide #6 and ask a volunteer to describe that process. [Sunlight, water, and carbon dioxide
are absorbed by the plant. The plant then uses them to make glucose (sugar), which is the
energy/food for the plant. Oxygen is also produced by the plant in this cycle, and is released
into the air.]
Ask students how photosynthesis is connected to the production of glucose, or sugar. Ask
them to discuss in their teams how this information could help them come up with ideas for
solving the problem. (They might try to find a way to speed up the rate of photosynthesis in
plants so that sugars would be produced faster.)
Floating Leaves Grade 7 science Q 1 Lesson
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• Guide students to decide to create a system that increases the rate of photosynthesis and
thus the quantity of sugars plants produce. (A system is a set of procedures and activities
designed to solve a problem.)
Say: Asking good questions is an important skill for engineers. So let’s identify some
questions we need to answer.
Let students make suggestions. Then lead students to see that they also need answers for
these questions: Show Slide #7.
Again indicate the RESEARCH stage and explain that they are going to do some hands-on
research to get information for their project.
PREPARE TO COLLECT BASELINE DATA (10 MIN)
Explain the experimental process they will use. Show Slides #8 – #10, which include a
video to help them understand the technique they will use in preparing leaf disks. (The
video can also be located at http://tinyurl.com/3lr6d3)
Help students understand how this experiment will demonstrate the rate of
photosynthesis. Following Slide #10 explain that normally the leaf disks would float. When
they force the solution into the air spaces in the leaf disk, the density increases and the disk
sinks.
Answers to Slide #7 for Teacher’s Use
1. What can we do to increase the rate of photosynthesis? (Two things they can look
at to increase the rate of photosynthesis are carbon dioxide and light.)
2. How will we know that the rate of photosynthesis has increased? (Oxygen is given
off as a gas. They can get a baseline measurement on how rapidly oxygen is
produced. Then they can adjust the light and the carbon dioxide, and measure to see
if they have increased the rate of photosynthesis.)
3. How will we know that more sugars are being produced? (If photosynthesis is
occurring more rapidly, then more sugars are being produced.)
Note: A “floating” leaf is any leaf that is not touching the bottom of the cup or other
leaves stuck to the bottom of the cup.
Floating Leaves Grade 7 science Q 1 Lesson
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Explain that the solution includes a small amount of Sodium bicarbonate, or baking soda.
This provides the leaf disk with a source of carbon for photosynthesis, much as carbon
dioxide does in the air. As photosynthesis occurs, the leaf disk produces oxygen which is
released into the interior of the leaf. This makes the leaf lighter and causes the disk to rise.
The rate at which the disks rise is a way of measuring the rate of photosynthesis.
Probe for questions before students start the experiment.
Remind teams of their lab safety procedures, including:
1. Wear goggles and gloves when pouring all liquids.
2. Do not look directly into the light.
3. Use caution when using an electrical device (such as a light) around liquids.
CONDUCT THE BASELINE DATA TEST. (20 min.)
Call attention to the folders. Tell teams to remove the Experiment Procedures, the Floating
Leaves Baseline Data Chart, and the Floating Leaves Data Graph from their team folders.
Explain that students should use the Experiment Procedures handout to be sure the team
members follow the procedure correctly. Also be sure that they take turns performing tasks
and share responsibilities.
• Pool the data. As each team finishes the experiment, instruct teams to fill in the number of
leaf disks that were floating every minute on Day 1 Collective Data Chart you prepared (see
Teacher Preparation: Day 1). Keep the chart up all day and let all classes fill in their data (the
number of disks floating each minute.)
At the end of Day 1, have some students in the last class tally the number of disks floating
each minute and write this number in the “Total disks” row. Then, on Day 2, students will be
able to look at the pool of data from all teams and use this larger, more reliable set of data
to infer baseline information.
Tell students to discuss with their team some possible ways to increase the amount of
photosynthesis that occurs in the plants. Now that teams have baseline data, they should
Note: These steps should be performed with some or all of the room lights turned off. The room should not be dark, and there should be adequate light for students to see easily, but the room should not be brightly lit.
Floating Leaves Grade 7 science Q 1 Lesson
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continue the research step by investigating how light and sodium bicarbonate affect
photosynthesis.
Tell teams that they will be given the options of manipulating one of the following variables
for Day 2:
1. The color of light
2. The amount of sodium bicarbonate.
• Wrap Up. Ask each student to write on an index card the problem the team is working to
solve, and to give you the card when they leave class.
Day 2
REVIEW THE ENGINEERING DESIGN PROCESS (1 min.)
• Show Slide 12 (the EDP) and ask students what stages they worked on yesterday. (DEFINE
THE PROBLEM and RESEARCH.) Explain that we will continue the RESEARCH stage today
before we begin to DEVELOP and CHOOSE solutions to the challenge.
ANALYZE DAY 1 DATA (5 min)
• Review the data from the baseline experiments. Call attention to the Day 1 Collective Data
Chart on which all classes recorded their results.
Ask teams to think about what these numbers and graphs tell us about the amount of
photosynthesis that occurred in the white light condition with a 2% sodium bicarbonate
solution. (Students should look at the “Total disks” column for each minute.) Instruct teams
to get the Baseline Data Analysis handout from their folders.
Tell them to examine the chart and write answers for the questions. After 3 minutes, review
the answers with them to be sure all teams have written the correct information.
Ask teams to look at the Floating Leaves Data Graph they drew and see if they can decide
whether one variable made more difference than the other.
Ask teams the following questions and guide them to conclude the following answers:
1. What is the reason we are trying to increase the rate of photosynthesis? (So that the increased amount of sugars produced by photosynthesis can be used to produce biofuels.)
2. How will we know if the rate of photosynthesis is increasing? (Leaves may begin to float earlier, or to finish rising to the top sooner.)
Floating Leaves Grade 7 science Q 1 Lesson
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3. What do leaves rising have to do with photosynthesis? (The oxygen produced by
photosynthesis makes them rise.)
PREPARE TO TEST (4 min.)
• Explain that to increase the rate of photosynthesis students need to learn more about
some variables that affect the rate of photosynthesis. They will continue the RESEARCH
stage of the EDP today. They will research how different variables affect the rate of
photosynthesis. Then they will use the data to make informed decisions to engineer a
system to increase the rate of photosynthesis.
• Ask students to get these 2 handouts from the team folder:
1. Experiment Procedures Day 2: Test Colored Light
2. Experiment Procedures Day 2: Test Carbon Dioxide Production.
Direct students attention to the three variables listed on each page. Explain that you will
assign one variable to each for testing. Half of the teams will test light variables and half of
the teams will test sodium bicarbonate variables.
• Assign a different one of the 6 variables to each team. (If you have more than six teams,
some variables may be tested by more than one team.)
LEAD TEAMS TO CONDUCT TESTS (20 min.)
• Lead students to repeat the procedure they used in Day 1, using the modification they
made for their variable. Remind students to record the data they collect on the Single
Variable Data Chart from their folders and to add plot the data in the Floating Leaves Data
Graph (also in their folders).
Display the Day 2 Collective Data Chart you prepared (see Day 2 Teacher Preparation). Tell
students to tally their data in the class chart as they complete their tests.
• Walk around and monitor the teams’ work. Be sure they are working smoothly as a team,
are setting up and conducting the experiments correctly, and are recording their data.
DEVELOP AND CHOOSE (15 min.)
Indicate the DEVELOP and CHOOSE stages of the EDP on Slide #12. Tell students they are
ready to launch into these two phases and develop a plan for increasing the rate of
photosynthesis.
Floating Leaves Grade 7 science Q 1 Lesson
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Use data from to the Day 2 Collective Data Chart to make decisions. Explain that teams
are now going to plan their system to increase the rate of photosynthesis. They will choose
two variables – the color of light (including white) and a solution strength they want to use.
Ask students to look at the information the chart contains about light and % solution and
make some decisions. Guide them as they discuss what they can learn from the chart to
help them make these choices.
Show Slide #13 and explain that these are the choices students have for each variable.
Point out that each team will need a first choice and a second choice for color of light they
would like (unless you have enough cellophane or colored filters for multiple teams to
choose the same color).
Tell teams to design the system that they believe will increase photosynthesis above the
baseline rates from Day 1. They should get the Biofuel Production Design Proposal from
the Team Folder. When they decide on a plan, they should fill out this sheet.
Wrap up. Before students leave class, check for understanding by asking these questions:
1. What is the role of the sodium bicarbonate in our testing? (It is the source of
carbon dioxide which is needed for photosynthesis.)
2. What causes the leaves to rise? (Photosynthesis converts the CO2 to O2. The O2 gas
fills the leaf spaces and causes the leaf to rise.)
Tell team members to turn in their Design Proposals along with their Team Folders as
they leave class.
Teacher note: Blue and red lights generally show the fastest rate of photosynthesis.
Floating Leaves Grade 7 science Q 1 Lesson
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Day 3
HELP STUDENTS RELATE THEIR WORK TO THE ENGINEERING DESIGN PROCESS (3 min.)
Invite volunteers to briefly describe what stages of the EDP they have done so far, and
what they did during each stage. Show Slide#14 as they do so. (Remind them that they
have been communicating throughout the process by sharing and discussing data.)
Remind students that they have a problem to solve (How to increase the rate at which
plants produce sugars in order use these to produce biofuels.) Today they are going to create
and test their system. Show Slide #15.
GUIDE TEAMS AS THEY TEST THEIR DESIGN (20 min.)
Establish that teams have the materials they need. Give teams the correct colors of
cellophane for the light they will use in their design. Tell a member from each team to bring
the beakers up to the place you have set aside for preparing the sodium bicarbonate
solution, and guide them as they prepare it correctly. If a team wants to increase the
percentage of sodium bicarbonate above 16%, be sure they calculate the amount correctly.
Instruct teams to begin testing. They will conduct the tests in the same way as in the
previous two days. They should record their data on the Sugar Production Test handout
from their Team Folder.
Collect class data. When students complete their testing and record their data, ask them to
write their data on the Day 3 Class Data Table. This table will allow teams to compare
results and determine which system design performed best. (Be sure to assign each team a
number so they will know which column to use.)
ANALYZE AND EVALUATE RESULTS. (15 min.)
Lead teams to compare their results with the baseline data and determine if they
improved the rate of photosynthesis above the baseline. They will need to look at their
Floating Leaves Data Graph handouts from their team folder.
Students will need to consider how to determine if they increased the rate of
photosynthesis by considering and discussing the prompts on Slide #16.
Floating Leaves Grade 7 science Q 1 Lesson
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Lead teams to analyze the Day 3 Class Data Table. Leave Slide #16 up as students discuss
and compare the class results. Which team designs seemed to increase the rate of
photosynthesis the most? (Students should base responses on Slide #16.)
After deciding on some team designs that seemed to work well, tell students they need to
know what variables these teams used. The teams selected should share their variables
with the class. Write the variables on the board as the team shares them.
Ask teams to use the chart to make generalizations about what variables seemed to make
the most difference. Did the highest rate of photosynthesis come from teams that used a
particular color of light? Did the highest rates come from teams that used a particular
concentration of sodium bicarbonate solution? What general conclusions, if any, can
students draw from this table? For example, can they answer this question from this data
set?
What variable(s) seemed to increase the rate of photosynthesis?
Also ask students if there seem to be some sources of error in the data. In other words, did
two similar designs get very different results for some reason?
REDESIGN (10 min.)
Instruct teams to decide what changes to their design they would make to increase the
rate of photosynthesis. Tell teams they will use their new design to write a request for
funding to start their own biofuel production firm.
Tell students to get the Official Funding Proposal handout from their Team Folder. Tell
them to complete all sections of the proposal in 8 minutes.
Exit Question. Show Slide #17. Tell students to follow the instructions on the slide and to
turn in the index cards as they leave the room.
Assessments: Possible assessments include the Floating Leaves Data Graph, Baseline Data
Analysis, and the Official Funding Proposal.