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Brassica, Butterflies and Caterpillars

Related Topics:

  • Starting with students
  • Making space to learn
  • Level of structure/guidance provided



  • Practice making an argument with evidence.
  • Compare and contrast qualitative and quantitative data.
  • Practice collecting and analyzing quantitative data.
  • "Understanding" big ideas related to heritability like; disease, genetics of complex behavior like alcoholism, variation in (human) populations and evolution by natrual selection.



Follow up Questions after the lesson:

  1. What is still unclear about the lessons objectives or methods?
  2. What new questions do you have about the objectives or methods?





This week we want to look at the role that genes, environmental factors, and selection play in an organism's phenotype. To do so we will look at the phenotypes of populations of the plant Brassica rapa ("fast plants").

The plants you'll be looking at were all seeded at the same time several weeks ago. There are two genetically different populations (A and B) and each was grown under four different conditions (high light and  high fertilizer, low light and high fertilizer, high light and low fertilizer, low light and low fertilizer). To get started, examine specimens of each with the following questions in mind. Neither population is genetically homogenous, so keep in mind that there may be some variation due to unknown genetic factors.

  • Do genes affect plants?
  • Do environmental variables affect plants?
  • Are there characteristics that are affected only by genes, only by the environment, by both?

The answers to these questions are likely to be different for different plant characteristics. After looking generally at the plants, pick several different qualitative and/or quantitative characteristics to study in more detail. Among the latter, include a particular quantitative characteristic of these plants: the number of petiolar trichomes on the first true leaf. Describe relevant observations and interpretations in the lab forum area.

We will compare data on the number of petiolar trichromes in our plants with data from other laboratories in populations derived from ours by using as parents only those individuals having a number of trichomes greater than 90% of the population to determine if this characteristic is subject to evolutionary change. (Click -here- for a student manual for this experiment).




A Problem Based Learning Activity



LIFE CYCLE OF Pieris Rapae





  • Practice student directed investigation.
  • Explore factors influencing animal behavior.
  • Gain experience in analysis and presentation of data.


Behavior is the sum of the responses of an organism to internal and external stimuli. Ethology is the study of animal behavior in the context of evolution, ecology, social organization, and sensory abilities of an animal. There are two basic categories of behavior: learned and innate (inherited) behavior. Experimental evidence suggests that the basis of both lies in the interaction between the animal’s genes and it's environment. This interaction influences how genes are expressed and regulated as well as generating long term effects in a species if differential selection forces are present. As with all genetically controlled features of an organism, behavior is subject to evolutionary adaptation.  As you study animal behavior in this lab, think in terms of both proximate causes, the immediate physiological events that led to the behavior, and ultimate causes, the adaptive value of the behavior (Morgan & Carter, 2002).

Feeding is arguably one of the most important of all animal behaviors.  We will investigate feeding behaviors of the larva (caterpillar) of the Cabbage White Butterfly (Pieris rapae). While the larvae are infamous as a worldwide pest of brassica crops (such as cabbage, broccoli, and canola), the cream-colored butterflies are important pollinators of many plants (  During this activity, our goal will be to determine if the caterpillars have a preferred food and what factors might be influencing their “choice”. 



  • Discuss/define "behavior" - (see Langton's Ant)
  • Observe caterpillars and butterflies.
  • Summarize observations - what is known?...what is unknown?
  • Devise experiments to test the summaries.


  • Caterpillar Option:
    • In behavioral arenas, set up a choice test between three food options.
    • Place 3 foods equidistance around the perimeter of the arena.
    • Place a single larva in the center of the arena.
    • Observe, time and take notes on the activities and movements of the larva
    • Repeat as many trials as time allows
    • Revise summary based on experimental results

Pieris larva in "behavioral arena" - food preference assay

PROCEDURES (for caterpillar option):

  1. Clean and dry a glass bowl provided in lab.
  2. Obtain one piece of each food type supplied and place them equidistance around the perimeter of the arena.
  3. Obtain a larva and place in the center of the arena and note its sex.
  4. Observe, time and take notes on the activities and movements of the larva.  We will pool all the data to obtain a frequency of larval visits to each food type.
  5. When the larva has moved to a food and begun eating or stayed for three minutes, start a new trial at step one, but change the placements of the foods and the position of the larva (i.e., change the direction the head is facing when placed in the arena).
  6. If time allows alter the experiment to test a new question that arose from your initial observations.  What is the stimulus?...color? …odor?
  7. Conduct a Chi-Squared test of significance on pooled, class data. Your lab instructor will guide you through this at the end of lab.




3.heritability_lab.08.doc582.5 KB


Deborah Hazen's picture

So many questions...

I appreciate that the fast plants inquiries that Wil shared are little question seeders. I left the lab thinking that I wanted to set up a fast plants corner in the classroom just for me---just because I was curious and excited to do the initial trials AND then figure out what else I could investigate from there. Opening the inquiry up so that students decide what kind of data they will collect and how, what conditions they will set up, what ideas they want to test...all of this is the essence of a great inquiry. The topic or theme (plants, life cycles, environment vs. genes....) creates a natural boundary that is not too restrictive and offers kids the opportunity to play with the toys that you as the teacher have provided.

Wil's inquiry met a couple of other criteria for a good inquiry lesson--it was self-generating---I just can't imagine any student feeling "done" with the whole thing after one day or week or even the span of the unit. It was also an activity that calls on students to surprise me, be creative--there wasn't a whole lot of room for kids to just replicate or regurgitate--the onus is on the student to tell/show me what they are thinking/think they know/are curious about---it is the kind of inquiry that helps me safeguard against inserting too much teacher into the process. It is the kind of inquiry that will lead kids (I think naturally) to collect content knowledge because they want to know more. It is the kind of inquiry that lends itself well to interdisciplinary study. Finally, it is the kind of inquiry that will capture the attention of and draw on the experiences of folks outside the classroom, so that when my students invite them in they will experience other students and adults being genuinely interested in their findings, questions and ideas.

Brie Stark's picture

Developing Own Project

From a student perspective, I thought that this project could be expanded into an inquiry-based project developing hypothesis creation and then subsequent self-creation of an experiment to test the hypothesis.  I think that this would fit well into the inquiry system because the laboratory would be entirely subjective: the student would have to write out their hypothesis (or hypotheses), the methods they would use, detailed experiment steps, summaries, graphs, etc.  This would be great for an upper level high school class because of the freedom of the project.  We did something like this in chemistry, where we had to design our own project in order to test a given hypothesis (like the gas law); it didn't matter if our experiment agreed or disagreed with the gas law, but rather, what we did to develop our project.  This stressed the developmental aspect of experimentation rather than the conclusion.  The student had to explain their own thoughts, describe what resulted (both favorable and perhaps unfavorable) but also analyze how they, themselves, had designed the project and what improvements could be made in the future.  This gives them an upper-hand in the learning process because, instead of being given a concrete lab with set instructions, they leave themselves open to exploring (and, of course, failure) but ultimately learn more, especially if they are hands-on learners, like myself.


Syreeta Bennett's picture

reflecting on the brassica plant lesson

In kindergatren they study trees the first unit. In the unit they are asked what a tree needs to grow. The curriculum wants them to know that a tree needs air, water and sunlight.  I will then asked them what happen if we change any of those things, will all the plants grow the same. We as a class could set up each experiment and they could record their observations through drawings and simple sentences. When we finish I can ask them is there other things we can do to change our experiment. It is open to them, some might ask what if we add plant food,  what if we try sand, or if we grow them in front of an air-conditoner. I do believe that this lesson can have many extensions based on their own inquiry. 

joycetheriot's picture

Finshed Product

Thanks Wil, for a terrific lesson today! As you described the lab I allowed my thought process to help guide my ideas for implementation in my own classroom. i want to enable the students to have their own space/time to create meaningful understandings but I don't want to overshadow the joy of discovery with procedural confusion. I spent a long time starting with the teacher's guide and then pouring out a reasonable constructed surface for my students to place their ideas. Lastly was the lab frame that will get at their observation within a managed matrix. i included possibilities for further research and am tickled that I can share this with other Bio teeachers who may want to use my lab set-up.

I'd share the constructed product on the forum but my brain operates in MS Word and I can't handle the web page's dislike of it.

Fabulous day, I know that I will continue to polish this lab but I'm so happy to have the product!




Stephen Cooney's picture

fast plants, slow teachers!!

 Can't wait to share this with the Bio teacher at my school and my dept head who teaches integrated science.  Both of them will find this useful.  I liked the discussion at the beginning of the lesson, while I might have wanted more direction, I was engaged.  The open global discussion, followed by the focused quantitative lab, connected back to the global questions put an interesting spin on things.  Here is a link to software called Logger Pro, produced by a company called Vernier.  You do not need their hardware to make very effective use of the software.  When looking at the graphs, Ed suggested that the area ‘under the curve’ should be the same, I thought of Logger Pro; cut and paste the data from Excel and it will do the integration for you, for a quick comparison.  That one tool is the tip of the iceberg, it is a superb analysis tool.  Site license is only $189.

Dalia Gorham's picture

deidre & dalia

We could use this lesson as a group guided inquiry project.  This project/investigation will be used with a 3rd grade class and is alligned with the core curriculum & standards-  "Generate questions about an object, organism, and/or events that can be answered through scientific investigation."


We would conduct an experiment using identical seeds/plants using artifical light vs. sunlight and tap water vs. bottle water.

Our students will do daily observations and look at how environment affects plants.

Our hope is that our students will develop their own questions to later develop their own experiment and lead to an independent inquiry project.

Syreeta Bennett's picture

reflecting on the brassica plant lesson

In kindergatren they study trees the first unit. In the unit they are asked what a tree needs to grow. The curriculum wants them to know that a tree needs air, water and sunlight.  I will then asked them what happen if we change any of those things, will all the plants grow the same. We as a class could set up each experiment and they could record their observations through drawings and simple sentences. When we finish I can ask them is there other things we can do to change our experiment. It is open to them, some might ask what if we add plant food,  what if we try sand, or if we grow them in front of an air-conditoner. I do believe that this lesson can have many extensions based on their own inquiry. 

Judith Lucas-Odom's picture

Fast Plants 101

I was asking myself how can I adapt this to meet my curriculum ?  I decided to use the fast plant and cabbage butterfly to investigate life cycles and environmental issues.  When I teach these areas in the late winter and spring, I will incorporate the Brassica butterflies.  I would also like to introduce the fast plants in September so that the students can write in their journals about what they see; just open inquiry, maybe even make suggestions of what might happen next.  Since I am not aware of what level I will have in the fall, I will probably do an introduction lesson and then plan for future inquiry lessons when I know my grade level.  Each time I see the fast plants, I get a new understanding and awareness of how useful fast plants can be in inquiry.  I will also tie my lessons into a multiple intelligence format.  Thanks for the inquiry lab, I learned that sometimes open inquiry,(no directions just do your own thing), can be an excellent way to find out how people think and organize information.

Moira Messick's picture

Fast Plants

I really enjoyed today's lessons on fast plants.    Beginning  the class with a discussion of disease to capture student interest is a good idea.  Although I see the value in allowing us to come up with the goal of the lab at the college level.   In my classroom I would want to determine (with the students) the overarching goal before we would go to the lab.  In this case, the goal would be to collect data in order to determine which traits were:  not genetically linked, 100% genetically linked or both genetically or environmentally linked.  I think we would collectively brainstorm characteristics for everyone to record into their data tables.  At that point I would set them loose on the procedures:)

I liked the way Wil stopped throughout the lesson and said "Are you guys okay with that language?"  It was kind of a backdoor approach to integrating the ever-important content within a context. 

When we reconvene, we would compile the data on the board.  Students would individually journal their interpretation of the data.  After "think, pair, share" we would discuss results as a class then take the opportunity to engage into inquiry.  I would ask students where they would like to go from there and get out of their way.  I would remain a facilitator who would help them formulate an answerable question, find relevant sources and encourage them to ask questions along the way.

Diedre Bennett's picture

I enjoyed today's lesson. 

I enjoyed today's lesson.  Using qualitiative and quantitative datas to determinef rather a trait is genetic or casued by environment helped me to think "outside the box" on this topic.  The lesson can for many grade levels.  Dalia and I are deciding how to adapt this for her thrid graders.  We will probably only use two variables.



GShoshana's picture

today's lesson

Because I teach language, I cannot see myself using this lesson in my teaching.  But, this lesson made me think more about my students and the things that influence them and their behavior.   Some basic behaviors come from genetics, but students are also influenced by the environment and some of their behaviors and thoughts can be changed based on what they want in their life.  This information that I learned from the lesson will help me and other teachers understand the way that students react and respond to things, and that it can somewhat be based on the environment of the classroom or their environment at home.  The lesson made me understand the need to support students and create positive learning environments.


RecycleJack Marine's picture

Yellow Plants

Dear Mr. Franklin,

What an amazing experiment you used with your Biology students. I took a class on these plants several years ago and never figured out how to connect it to my third graders. Now I understand what the objectives were and as I own plant growing systems, I think I can create a version of the set up here at the college.

I did not understand the graphing you modeled today in the class. But I think I can use some of the findings by placing them in a graph format.

I think I could bring this down to a life-science activity for grades 2-5 in an elementary school setting. Of course we would be studying life cycles of animals and plants. Students WBAT describe what plants need to survive and what plants butterflies depend on for living. I would like to create a lesson plan using Fast Plants, but as this precise moment today, I am too focused on my interview later today near Chinatown.

Kathy Swahn's picture

great morning lesson

I found this lesson very useful for a guided discovery lesson. It lends itself to huge variations for ages and abilities. I like the idea of fast growing plants for impatient children, often the wait time is the WORST! The extensions lend themselves very readily to become a unit.


Diane Balanovich's picture

fast plant adaptation

I could adapt this lesson by limiting the amount of variables that are being presented to the studnets. Also,I would direct my lesson toward the environmental factors that would be affecting the growth of the plant.   The observation and collection of data would be appropriate for first grade allowing students to use observations to draw conclusions about why the plants growth differs for each variable. We would probably graph the heights or the plants and draw conclusions, and also the length and width of the leaves, and number of buds and blooms.

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