Activity
11. On each group’s desk have a beaker containing
a mixture of flowers, a seed and an item easily identifiable
as a fruit. The presence of the flowers is often a good
catch for students. Ask them to describe either in words
or pictures the relationship between flowers, fruits
and seeds. Notebook Preassessment
2. Begin the flower dissection by handing a flower to
a student. Ask him/her to make observations and to describe
it. Hand it to another student. Continue to have students
describe it until no other observations can be made.
While students are describing the flower, have a student
write the observations on the board or overhead.
What is likely to occur is that students will want to
describe a particular feature of the flower but won’t
have the term for it. Don’t give them the term
yet. Have them just describe it. (Later they will make
the connection with the terms they are given.) This is
a good point to introduce the idea of flower anatomy-
that each flower part has a name so scientists can talk
about flowers using the same language. It also helps
botanists to categorize and identify flowers because
of the color and shape of particular parts. Tell students
that they will be taking apart a flower today so they
can understand how and why a flower functions as it does.
4. Students observe their own flower, describing it and
drawing it in their notebooks, labeling the parts as
they are identified.
5. Pass out a flower to each student. Once all students
have a flower, ask them, "Why do flowers have petals?" They’ll
probably know that they are for attracting pollinators.
It’s the flower’s way of dressing up. Explain
that all the petals together are called the corolla-
a word related to the word corona meaning garland or
crown.
6. The teacher should begin with the petals then have
the students remove and count the petals of their flowers,
taking note of this in their journals. Now the sepals,
peduncle, receptacle, stamens and pistils should be visible.
One by one draw the students’ attention to each
of these areas. Have them use their eye loupes to look
closely and to draw diagrams of each part. Ask what they
think each part is for. (They will be able to see that
the sepals once were the covering for the bud, and notice
that the peduncle supports the base of the flower.)
7. Give the students time to use color pencils to make
distinctions in their drawings. Give them opportunities
to ask questions and clarify understanding.
8. Have the students remove one entire pistil (they may
have to dig down to get the ovary) and look at it closely.
Look at the stigma, style and ovary. They can even open
the ovary and look inside. They should draw, label and
write the function of each part. Do the same with the
stamens, anther and filament.
9. Having identified the anthers, stamen and stigma ask
students how they think pollen gets from the anthers
to the stigma. Introduce the idea that it is more beneficial
for plants to cross pollinate, that plants are designed
to have pollen move from one plant to another. Looking
at the flowers in front of them can students identify
how pollen might move from one plant to another? Have
students suggest methods of pollination. Provide the
definition that pollination is the movement of ripe pollen
to a ripe stamen.
10. Provide students with the attached chart. Students
should be able to suggest wind, water, insect and bird
as vectors for pollination. Have them observe the flowers
again and identify what factors are necessary for which
type of pollination. Once the class has correctly identified
a structure as appropriate for a type of pollination
they should note that in the chart also. Direct students
to the website: http://www.learn.co.uk/default.asp?WCI=Unit&WCU=2330 This website has some simple diagrams that will support
students’ comprehension of pollination. Students
should draw flowers on their charts that represent each
form of pollination.
11. Assessment: Have students identify the parts of an
unknown flower. They should make suggestions as to how
the male and female structure organization plays a role
in pollination.
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Assessment |
