Plant Tropisms: Responses of Plants to External Stimuli
Lesson Plan on types of plant tropisms and the integration of math to science
By: Craig O’Connell
A. State Standards Addressed
a. Standard 6.1: The student will demonstrate an understanding of
technological design and scientific inquiry, including process skills,
mathematical thinking, controlled investigative design and analysis, and
problem solving.
i. Indicator 6-1.2: Differentiate between observation and inference
during the analysis and interpretation of data.
ii. Indicator 6-1.4: Use a technological design process to plan and
produce a solution to a problem or a product (including identifying
a problem, designing a solution or a product, implementing a
design, and evaluating the solution or the product).
iii. Indicator 6-1.5.
Use appropriate safety procedures when
conducting investigations
b. Standard 6.2: The student will demonstrate an understanding of structures,
processes, and responses of plants that allow them to survive and
reproduce.
i. Indicator 6-2.1: Summarize the characteristics that all organisms
share (including the obtainment and use of resources for energy,
the response to stimuli, the ability to reproduce, and process of
physical growth and development)
ii. Indicator 6-2.8: Explain how plants respond to external stimuli
(including dormancy and the forms of tropism known as
phototropism, gravitropism, hydrotropism, and thigmotropism).
B. Objectives
a. Students will learn about the various types of plant tropisms
b. Students will learn how to scientists conduct research.
c. Students will learn how to make bar graphs
d. Students will be given plants which demonstrate various types of tropisms
and each group of students must pick which tropism their plant is
demonstrating
e. Each group will be given a plant. They will hypothesize what will happen
when the plant is touched and try and develop reasoning as to why this
plant might respond to touch.
f. Students will do a laboratory exercise graphing the amount of time it takes
for their plants to response to touch (thigmotropism)
C. Lesson Plan
a. Engage. The lesson will begin with a quick PowerPoint presentation. The
PowerPoint presentation will introduce the students to the various types of
tropisms: phototropism, hydrotropism, gravitropism, and thigmotropism.
Each type of tropism will contain either media or actual plant
demonstrations. To engage the students, a variety of inquiry-based
questions will be asked relating to why plants may respond to various
stimuli.
b. Explore. After the lecture the instructor will break the class into four
different groups. Each group will be given a bug eating plant (sundew,
purple pitcher, or Venus fly trap). Prior to observing the plants, as a class
we will learn how scientists conduct research in the field. This will
require the students to make observations, hypothesis/hypotheses and
participate in an instructor led laboratory exercise. Students will learn
how mathematics is a common technique researchers use to explore the
scientific realm.
i. Instructor will revisit independent vs. dependent variables.
ii. Instructor will demonstrate how bar graphs are made: linking
variables to their position on a graph
iii. Instructor will lead class in a lab-based exercise explaining what
will be done with each plant
iv. Instructor will give each group one stopwatch
v. Each group will drop one insect into each one of their plants and
will record the amount of time it takes for one of their bug eating
plants to feed (prior to this exercise, students will have watched a
QuickTime video demonstrating how these plants feed so the
students will know exactly what to look for)
vi. Instructor will make table on board and as each group finishes, a
group representative must write their feeding time on the board
vii. Once each group completed the exercise, students will take out
their lab manual and create graph (independent variable: Plant
type or group number vrs. dependant variable time of capture).
viii. Instructor will assist in graph making and will ask students to
discuss results to determine if there were differential responses by
plant/group and why these differences occurred.
c. Explain and Elaborate. After this exercise, students will remain in the
same groups and each group will be given one mimosa pudica plant
(sensitive house plant). Students must not touch the plant prior to
exercise. Instructor will lead this lab and tell the students that this plant is
a rainforest plant that exhibits thigmotropism. Students will be asked what
thigmotropism is (review) and will be instructed to write definition down
in their lab manual. Following this definition, students will have to make
a hypothesis about what will happen when they touch the leaves of this
plant. Steps of this experiment will be:
i. Each group will have one stopwatch
ii. Teacher will make table on board which will require each group to
list their data
iii. Each group will touch their plant and record the amount of time it
takes for the leaves to fully close and stop moving. Once they stop
iv.
v.
vi.
vii.
moving each group will write down the time and will restart the
stopwatch.
Students will then start timing again to record the amount of time it
takes for the leaves to fully open back up again (maximum 3
minutes).
Students will write data on board
Students will look at previous graph they made and use that to help
them construct two different graphs in their lab manual:
1. Time for Mimosa pudica to close
2. Time for mimosa pudica to reopen
After constructing graphs, instructor will lead an inquiry-based
exercise having the students try to determine if all the plants
reacted the same way. If any difference occurs, students should be
asked to develop possible explanations as to why this difference
occurred. Answers will be written in lab manual under a
conclusions section.
d. Evaluate. This lab will be graded by a journal assessment. To be included
in their journal entry:
i. Various types of tropisms
ii. Hypotheses
iii. Observations
iv. Results (all three graphs: teacher-led graph and two student
graphs)
v. Conclusion: Why do you think plants responded this way?
1.
2.
3.
Post Lesson Notes from Teacher:
This was a very exciting exercise for the students and was easy to accomplish in a
100 minute lesson.
Students struggled with the graphing exercise but it was important for them to
understand how math is integrated in science.
This is an excellent exercise that will really enhance a plant unit in any grade
level. Seeing a plant move after a bug touches it or after they touch it is almost
magical to them and quickly gets the students engaged to learn.