Queens
College/CUNY
Education Unit
Fall 2009
Demonstration Lesson 2
Topic: The structure and function of flowers
Grade level/s: 9th grade, Living Environment
Science or Math background material for the teacher:
Instructional Objectives:
- Students will be able to draw and label the parts of a flower.
- Students will be able to describe the structure and function of each part of a flower.
- Students will discover that flowers have different shapes that are related to the functions.
- Students will be able to list several different flowers and describe how their structures differ.
National Science Education Standards met by this lesson:
Materials: picture of a stinking corpse lily, 10 dogwood flowers, 10 grass flowers, 10 hand lenses, pencils, paper
Procedure:
- motivation:
- Ask
the students if plants have reproductive organs? If they say yes, then
ask them if they know who was the first to realize this. Tell them the
story of Linnaeus:
http://www.ucmp.berkeley.edu/history/linnaeus.html
Linnaeus attached great significance to plant sexual reproduction, which had only recently been rediscovered. Linnaeus drew some rather astonishing parallels between plant sexuality and human love: he wrote in 1729 how
The flowers' leaves. . . serve as bridal beds which the Creator has so gloriously arranged, adorned with such noble bed curtains, and perfumed with so many soft scents that the bridegroom with his bride might there celebrate their nuptials with so much the greater solemnity. . . The sexual basis of Linnaeus's plant classification was controversial in its day; although easy to learn and use, it clearly did not give good results in many cases. Some critics also attacked it for its sexually explicit nature: one opponent, botanist Johann Siegesbeck, called it "loathsome harlotry". (Linnaeus had his revenge, however; he named a small, useless European weed Siegesbeckia .) Later systems of classification largely follow John Ray's practice of using morphological evidence from all parts of the organism in all stages of its development. What has survived of the Linnean system is its method of hierarchical classification and custom of binomial nomenclature.
- Ask
the students if plants have reproductive organs? If they say yes, then
ask them if they know who was the first to realize this. Tell them the
story of Linnaeus:
- advance organizer (if appropriate) - not needed
- Describe your procedure step by step
- Students should form groups of 3 to 5 students (cooperative, collaborative learning)
- Pass out flowers to each student.
- Make a sketch of your flower. Record your observations. Why does the flower have that particular structure? Is there any advantage to that particular structure?
- Are all flowers shaped like this? (Inquiry)
- Now start introducing terms for the features the students noticed.
- Hand out a completely different flower (e.g. a grass flower)
- Follow the same procedure.
- Why do the two flowers have different shapes?
- Is shape the only important difference between flowers? What else might be important? What are some examples?
- Does anyone know what this flower is? Why is it shaped this way?
- Closure - Read a poem about flowers.
The modest Rose puts forth a thorn,
The humble sheep a threat'ning horn:
While the Lily white shall in love delight,
Nor a thorn nor a threat stain her beauty bright.
Homework: have the class bring in a flower, write a poem about a flower
Adapatations for students with disabilities: Visually impaired students can still do this activity. Use two different flowers that are large enough so that differences can be felt by touch alone. Include one flower with scent and one without.
Multicultural Connections: Talk about uses of flowers in different cultures. Find out the national flowers of different countries and describe their structure and function.
Possible ways technology might be incorporated: You could have students take digital photos of flowers and then make a PowerPoint presentation or web site where they label them and include details on each type.
Assessment (How would you assess whether the students have accomplished the objectives?)
You could give them a new flower and ask them to describe how that flowers structure is adapted and where it might come from.
Extension activities: Write a poem on a flower, discuss pollination, grow pollen tubes and time the growth of different species.