Presenting Scientiﬁ c Findings
In the fourth and ﬁ nal section of the unit students must present their own “scientiﬁ c story” of what happened on the island: Why did the ﬁ nches die and how were the survivors able to live?
Students make posters that show key ﬁ ndings of their investigations, and they summarize their conclusions in an oral presentation. They may use journal entries to generate their story and cite data collected from the computer software as evidence that supports their story. During the presentations, classmates ask questions and evaluate each others’ stories. In this process they develop skills for constructing scientiﬁ c arguments and communicating scientiﬁ c results. An important part of this process is to help students see that there are a number of ways to interpret the data and construct a coherent argument that can be backed up with the data.
To put closure on the unit, once the student presentations conclude, students watch the rest of the New Explorers video to learn about and compare their own answers with the answers developed by the Galapagos scientists.
Important ideas to discuss during the presentations and in the concluding discussions include these key components of natural selection:
— do students recognize that there was variation in different ﬁ nch traits? Ask students
what the source of this variation is, whether the advantageous and less advantageous beak existed in the
ﬁ nch population before the drought.
• Changing distribution of traits
— discuss the distribution of beak sizes in the population before
and after the drought. It is important to understand how this change in the average has occurred. Have
individual birds changed in their beak length? (No.) Then why is the average length different?
— ask students to speculate about what might occur in the ﬁ nch population under
another pressure, asking them to talk about advantages of traits and distribution of traits, or ask them
to speculate about other organisms.
In preparation for an oral presentation, students will create a poster presentation
which will include a written story describing their ﬁ ndings, backed up with evidence that they have gathered from their computer investigations.
SG 3 A1, 2, 3, 4,
SG 5 A1, 2, 3, 4,
SG 10 A2; B1,
SG 3 A1, 2, 3, 5
• Student journals and printouts from computer
SG 5 A1, 6, 9
SG 10 A2; B1,
• Tell the students that their ﬁ nal report for the unit will be
• Using evidence from the computer investigation and pre-
viously written journal entries, they will need to choose the most important pieces of evidence which support
• Students should write their own “scientiﬁ c story” of
what happened on the island: Why did the ﬁ nches die and why did the survivors live? They may use journal entries and data from the computer to generate the story.
• Graphs included in the poster must be explicitly cited in
the written story. For example “We found that rainfall DID matter in the death and survival of the ﬁ nches (Graph 1).”
• Encourage students to use their artistic abilities to orga-
nize the poster. Important components to include are: Title, Names, Story, Evidence. Everything they want to include must ﬁ t on the poster itself.
In 1977 something happened to the finches in
the island of Daphne Major. Something caused 40%
of the finches to die, yet 60% of the finches managed
to survive. Why did the finches die? How did some
In 1977, the finches died because of the lack
of food that usually grows during the wet and dry seasons. In 1977 the amount of rainfall was very little compared to others, there was only 20 cm of the wet season and none in the dry seasons. The foods the finches ate are seeds from the Tribulus, Cactus, Portulaca and Chamae plants. In our research we found out that the most common food that grows alot out of all of them is the Tribulus plant. But the seeds of this plant are hard and all of the others are soft and medium. This makes it very hard for the finches to open unless they have very strong beaks. Your can see this happening in the finch profiles #5 - dry season of 77. This Tribulus plant grows in the dry season as well as wet seasons, all of the others don’t grow as much as the Tribulas plant in the dry seasons. So if there’s not much food in the dry seasons and the trubulus seeds is hard to open . How will the finches survive? The finches could only eat the seed if they had strong beaks to open the shell of the seed. So in conclusion our resources showed that most of the adults were the ones who really survived and the babies didn’t survive as much as the adults. The babies don’t have strong beaks and therefore wouldn’t be able to open the seeds. The adults have strong beaks and could open them easier than the babies. So who ever could open the seeds lived and the ones who couldn’t get it open starved to death.
Example Finch story from the poster of two seventh grade girls at Inter-American
Each team of students uses their poster to explain their ﬁ ndings from their investi
gation to the rest of the class. Other students in the class ask questions and can
make suggestions about their interpretation.
SG 4 A1, 2, 6;
SG 4 A1, 2, 5;
• Explanation Comment
sheets (enough for each student to
sentation skills and critical listening skills.
• The use of peer comment
• Present the guidelines about the presentation. Say:
“Your presentation should be about 5 minutes. Don’t just
read your story. Present the important ideas. Remember
that you are a team of scientists. You should each have
a role in your presentation; it will be up to your team to
decide how to divide up the contributions.”
• Give each group a chance to give their presentation.
Some teachers like to ask for volunteers; others pick the
order and call upon each group in turn.
• At the end of each presentation, encourage other stu-
dents in the class to ask questions and make suggestions.
Encourage students to focus on the important criteria for evaluating explanations: “Does the explanation ﬁ t the data they presented? Are there any important steps that are left out? Is each claim backed up by evidence? Have they demonstrated that they have ruled out alternative explanations?”
• Have students ﬁ ll out the Explanation Comment
• If students have practiced
A: Neat poster. Clear explanation. Evidence is cited and
shown and is clearly written. Some possibilities have been
leave the division of labor up to them. If you feel your
B: Neat poster. Clear explanation but some evidence may not
be cited or shown. Not sure of any other possibilities.
lines, some alternatives are to divide up the presentation
C: Fair poster. Fair explanation. Vaguely written explanation.
chance to talk, or the group can pick a spokesperson to give the main story, with
D: Poster present. Vague explanation. Not enough evidence.
the other members point-ing to and commenting on each part of the data when relevant.
A sample grading scheme for evaluating the student presentation and
I enjoy students’ thoughtfulness, their novel ideas, their thoughtful and never-ending questions. I definitely do not look for the right answer. I look for:1. A thoughtful approach – do they have a strategy, a
plan. Did they sort their data in a logical way?
2. Do they have a hypothesis and were they willing to
3. Are their explanations built piece by piece based on
4. Do they have several pieces of data to support
each claim or did they find one thing and leave it at that?
5. I look for passion – do they really believe what they
have concluded? Can they cite more evidence that supports their claim?
— Linda Patton, Von Steuben Metropolitan Science Center
Things you liked about the presentation and
Questions and suggestions
Students learn about the results of the Galapagos scientists’ investigations and
can compare the type of explanations their class developed with the current best scientiﬁ c explanation. A general discussion pulls together the core ideas of the unit.
SG 12 B1, 2, 3
SG 11 A4; C1
SG 12 A3; B1,
• What Darwin Never Saw
• Have a full-class discussion to pull together the main ideas that
arose in the presentations. Are all their stories very similar? Is
there one most popular theory? Are there a number of different
• Tell the students that you will be showing them a videotape in
which Peter and Rosemary Grant, the Galapagos scientists who studied Daphne Major, talk about their understanding of what happened during the drought of 1977.
• Discuss: “How is the work that we did like what the scientists
Points you may want to highlight include: “You have
gotten a taste of what science is like. Science is about coming
up with hypotheses, recording your ideas, testing your ideas,
and revising them. What you did is like what scientists do, only
on a smaller scale (less data, etc.)”
• Discuss: “Do you think they came to the same conclusion that
you did? Why do you think their answers might be different?”
Points you may want to bring out: (1) The scientists looked
at lots of data; your students have only had a small sample of
the data the scientists collected. (2) The scientists worked and worked on this question for months and months, looking at data, testing ideas, and arguing about them. (3) Scientists have lots of practice and training in looking at graphs, collecting data, and they are specialists in ﬁ nches, which allows them to pick out patterns in data.
• Explain the goal in doing this. “This assignment is not to see
‘who got it right and who did not.’ It took the scientists a
long time, and a process of looking at lots of data, and arguing
about it for months, in order to come up with their conclusions.
You have only had a small sample of the data the scientists
had to work with. As the scientists looked at more and more
data, their ideas developed and changed. At many points in
their process, they had several different hypotheses and were
not sure which was a better ﬁ t with the data. So your work is
like the work the scientist did in their initial stages. I am show-
ing you the videotape so you can see the type of explanations
that scientists develop when they work on problems like you
• Show the videotape segment in which the Grants discuss the
drought (approximately 36 min. 50 sec. on the tape).
• Have students discuss what aspects of their explanations were
• An additional topic for a closing discussion is to connect what
happened to the ﬁ nches to what occurs in natural selection.
An extreme drought is a selection pressure, something that causes problems for a population of organisms, in this case, the ﬁ nches. There is variation in the population; some ﬁ nches are heavier, some have bigger wing spans, bigger beaks, and so on. One of these features on which the ﬁ nches vary seems to be related to better survival. According to the Grants, the ﬁ nches with larger beaks could crack open the tribulus seeds that remained during the drought. Because of this, the surviv-ing birds tended to have longer beaks. Since many of the shorter-beaked birds died off during the drought, the average beak length has increased. When the remaining birds give birth to new birds, they will be likely to have longer beaks like their parents. Thus, we are seeing a gradual shift in the length of the beaks in the population because of the selective pressure. This is evolution by natural selection – a stress causes a change in the population on some feature.
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