Controlled Experiment
When Becky visited the Brooklyn Botanic Garden with her class she was impressed by the tall sunflowers
she observed growing in the Children’s Garden. She did some research on sunflowers and decided that
she wanted to investigate which growing conditions would support the growth of the tallest sunflowers.
Becky read about organic farming and she became interested in the use of compost and other organic
fertilizers for growing crops. She decided she wanted to test the effect of organic matter, compost in
particular, on the growth of sunflowers. To test the effects of increasing amounts of compost, she decided
to plant some seeds in compost alone, some in the perlite alone, and some in mixtures of the two that
contained different amounts of compost and perlite. The 3 mixtures she created were: 75% compost/25%
perlite; 50% compost/50% perlite; and 25% compost/75% perlite. This resulted in her planning for 5
different sets of pots. Becky used 3 pots for each soil mixture and 3 pots each for compost and perlite
alone. In each of the 15 pots, she planted 3 seeds.
Investigation Design
Title: The effect of compost on sunflower plant growth.
Research Question: How does the amount of compost (organic material) in a soil mixture affect the
height of sunflowers planted from seed?
Hypothesis: If sunflower seeds are planted in a soil mixture that contains mostly compost defined as 75%
compost and 25% perlite then they will grow into taller plants than those seeds planted in the other soil
mixtures because the organic materials in compost will provide the plants with nutrients that are
beneficial to growth and the perlite will retain water and provide air spaces for the roots to grow.
Independent Variable: Amount of compost added to soil mixture (%)
Change in
independent
variable:
100 % Compost
75 % Compost
25 % Perlite
50 % Compost
50 % Perlite
25 % Compost
75 % Perlite
100% Perlite
Number of
repeated trials:
3 pots
3 seeds per pot
3 pots
3 seeds per pot
3 pots
3 seeds per pot
3 pots
3 seeds per pot
3 pots
3 seeds per pot
Dependent Variable: Height of stem (centimeters)
Constant Variables: Number of hours of light, amount of water and frequency of watering, type of pots,
type of sunflower seeds, number of seeds per pot, temperature, humidity
THE EFFECTS OF COMPOST ON THE
GROWTH OF SUNFLOWERS
100% compost
75% compost-25% perlite
50% compost-50% perlite
25% compost-75% perlite
100% perlite
Final Average Height
(cm)
7.9
10.3
11.2
9.1
3.4
Comparing Height of Sunflowers in Different Soil Media (cm)
12
10
Height (cm)
8
6
4
Final Average Height (cm)
2
0
Soil Media
N, P, K and pH SOIL TEST RESULTS
Nitrogen Level
Phosphorus Level
Potassium Level
pH Level
Medium Type
Trial 1
Trial 2
Trial 1
Trial 2
Trial 1
Trial 2
Trial 1
Trial 2
Wiggle Worm
VH
H
M
L
VH
M
4
4
Perlite
L
L
L
L
M
H
6
6
VH=Very High
H=High
M=Medium
L=Low
I=Inconclusive
Percolation Test Results
Volume of water that percolated through (mL)
Wiggle Worm
Trial 1
Trial 2
100%
compost
75% compost
25% perlite
50% compost
50% perlite
25%
compost
75% perlite
100%
perlite
92
82.5
84
82
80
78.5
82
74
85
72.5
Conclusion:
My observations show that the sunflower plants in the 50% vermicompost-50% perlite mixture were the
tallest. My hypothesis that more compost, defined as a mixture of 75% vermicompost-25% perlite, would
provide more nutrients for the sunflower plants and cause them to grow tallest while allowing for some
root aeration, was not supported by the data.
The 50% vermicompost-50% perlite mixture were the tallest, with an average height of 11.2 cm. The 75%
vermicompost-25% perlite mixture yielded the second tallest plant height with an average of 10.3 cm.
The shortest plants were grown in 100% perlite with an average height of 3.4 cm. They were 7.8
centimeters shorter than the tallest plants grown in the 50/50 mixture. The second shortest plants were
grown in 100% vermicompost with an average height of 7.9 cm. They were 3.3 cm shorter than the tallest
plants grown in the 50/50 mixture.
According to the background research, sunflower plants need nutrients in order to grow, specifically
nitrogen, potassium and phosphorus. Sunflower plants require nitrogen “to form basic proteins,
chlorophyll, and enzymes for plant cells. Potassium is used by plants to produce sugars, starches,
proteins and enzymes. Plants also use potassium to regulate their usage of water” (Braswell, 2008).
Phosphorus is an essential building block of a plants’ DNA. It is used by plants for cell development and
growth. (Raven, 1999) Soil test results showed that the compost contains a high level of nitrogen, a low
level of potassium and trace amounts of phosphorus. It confirms that the organic material contains
essential nutrients which are important for plants. Plants growing in a soil mixture containing some
amount of compost will be provided with these nutrients. The nutrient tests revealed that perlite has low
levels of nutrients, so the 100% perlite may not have the necessary nutrient levels to support healthy plant
growth thus resulting in shorter plants. My percolation test results showed that the perlite retained
significant amounts of water, as did the compost. We did not conduct a test to determine the level of
oxygen within the soil mixtures. In a future experiment I would like to support my understanding that
perlite provides aeration in the soil. I can conclude that either 100% compost or 100% perlite does not
support the growth of plants because the 100% compost lacks aeration and the 100% perlite lacks
nutrients. Since the 50/50 mixture yielded the tallest plants, I can conclude that this mixture has an
optimum amount of nutrients and an optimum amount of aeration in the soil. The other two mixtures, the
75% compost-25% perlite and the 25% compost-75% perlite have adequate amount of nutrients, and
adequate aeration in the soil because both of those mixtures produced plants that were tall, however, not
the tallest.
Design Investigation
Ms. Hussain introduced her students to a unit on force and motion by giving them the opportunity to
experiment with making and launching their own straw rockets. She challenged the class to create a
rocket that could travel a distance of 15 meters in the shortest period of time. John’s team discussed all
the ways that they might change the rocket design so that it could cover the distance faster. They made a
list that included: change the length of the rocket’s body tube, change the number of fins, change the
length of the fins, change the type of paper used to construct the rocket model. The group hypothesized
that a rocket with a shorter body tube and larger fins made from photo paper would be more aerodynamic
and travel a further distance than a longer, heavier rocket. They believed that a longer and heavier rocket
would slow down the flight and wouldn’t fly as far before it dropped out of the sky. The group decided to
test one variable at a time, each variable being one aspect of the rocket’s construction they would change.
They agreed that in Test #1 they would change the length of the rocket’s body tube. For Test #2 they
decided to change the number of fins. In Test #3 they tried various fin lengths and in Test #4 they
constructed the model out of different types of paper. Students tested each of these components 5 times.
After testing these four variables, the students made a rocket whose length, number of fins, length of fins
were the measurements that gave the best results in each of their tests and they used the paper type that
built a rocket that traveled the distance of 15 meters in the shortest period of time. They then tested the
rocket with this final design to see if they had indeed built a rocket that could reach the 15 meter distance
in as short a period of time as possible.
Investigation Design
Test #1: Changing the length of the rocket’s body tube.
Title: The effect of body length on the speed a rocket travels.
Research Question: How will body length affect the speed at which a rocket travels?
Hypothesis: If the body length of a rocket is shorter it will travel faster than a longer body length for the
same design because there will be less drag on a shorter rocket due to its smaller surface area.
Independent Variable : Length of the rocket body (centimeters)
Change in independent variable:
5 cm
10 cm
15 cm
20 cm
25 cm
Number of repeated trials:
5 trials
5 trials
5 trials
5 trials
5 trials
Dependent Variable: Time it takes a rocket to travel 15 meters
Constant Variables: weather conditions, setting, launcher, fin size, number of fins, type of material used
to make rocket
After Test #1, the students repeated the steps above but modified the experimental design of the
experiments to investigate:
Test #2: Changing the number of fins on the rocket.
Test #3: Changing the length of fins on the rocket.
Test #4: Changing the types of paper used to construct the rocket.
Conclusion:
A rocket that is comprised of the various components that had the fastest transit time will be travel slower
than then rocket that is made only of the body tube.
When looking at the data we decided to calculate the speed of the rocket because it was difficult to
determine exactly when the rocket crossed the 15-meter mark. By looking at the average speed for each
trial we were able to see how manipulating the rocket changed the speed of travel as well as the total
distance that it traveled. The components that had the fastest times for their trials were the 15cm body
length, 2 fins, the 2 cm length for fins and the fins made of photo paper.
For the body tube length experiment we saw that the length that went the fastest was the 15cm rocket,
going an average speed of 12.03 m/sec. When we tested the number of fins, the rocket with 2 fins went
the fastest at 11.87 m/sec. The length of the fins also affected the speed of the rocket. The length of the
fin that traveled the fastest was the 3 cm fin, going an average of 11.75 m/sec. We also found that the
best type of paper to use for the fins was the photo paper, going an average of 11.80 m/sec.
When we put all of these characteristics into one rocket, we found the average speed of that rocket to be
11.83 m/sec. Even though that was faster than the average speed for the length of the fins experiment, by
.08 m/sec, and the paper type for fins, by .03m/sec, it was still not the fastest. The final design of the
rocket traveled .20 m/sec slower than the rocket that only tested the body tube length.
Every time something was added or taken away from the rocket, the mass of the rocket was affected.
Having a shorter body tube, meant that the rocket had a smaller mass. The force applied to this smaller
mass was not enough to make the rocket travel the required distance because the rocket was to light and
was more affected by air resistance. There has to be some balance between too light and light so that our
rocket can have optimal performance. As we continued our trials we noticed that there was a proportional
relationship between the length of the body tube and the speed at which it traveled.
The fins were added to the rocket to streamline or stabilize the vehicle. By altering the size and material
of the fin we again altered the mass, but by a much smaller amount. As can be seen in the trials, the effect
of this change by comparing the average speed of the 15 cm rocket with no fins, which was 12.03 m/sec,
to the average speed of the final design of the rocket, which was 11.83 m/sec. The additional mass added
to the rocket account for the .2 m/sec difference could.
For the challenge that we were given the fins were not needed. It just added additional mass to the rocket
that in turn slowed the rocket down. The optimal design for the challenge was just a 15cm body tube with
nothing added to it.
Field Study (A)
An Urban Advantage class visited the Bronx River with their teacher to study living and non-living
features of the wetland. After exploring different portions of the river, a group of 8th graders notice a
waterfall. They approach their teacher and propose to investigate the relationship between dissolved
oxygen levels of the water and the location upstream or downstream from the waterfall for their exit
project. The students hypothesize that the oxygen levels downstream from the waterfall generally will
have higher levels than upstream from the waterfall, because of the increased stirring of water as it flows
over the falls. The students decide to sample four sites along the river: 20ft upstream from the waterfall,
10ft upstream from the waterfall, 10ft downstream from the waterfall, and 20ft downstream from the
waterfall. Students decide to test oxygen levels three times at each location. They repeat this testing at the
same locations on the river two additional days.
Experimental Design of Science Exit Project
Title: The effect of location along the Bronx River on oxygen level of the water.
Research Question: How does the water fall on the Bronx River affect the water’s oxygen levels?
Hypothesis: If water is downstream from a waterfall then the dissolved oxygen will be higher than it is
upstream from the waterfall because churning of the water exposes more water to the air, which adds
more oxygen.
Independent Variable: Locations along the Bronx River (meters from waterfall)
Change in
independent
variable:
Number of
repeated trials:
20 feet upstream
from water fall
10 feet upstream
from water fall
3 tests
3 different days
3 tests
3 different days
10 feet downstream
from water fall
3 tests
3 different days
Dependent variable: Oxygen level of water (milligrams O2 per liter)
Constant Variables: Type of test kit; river.
20 feet downstream
from water fall
3 tests
3 different days
Data:
20 ft
Water Temp Upstream
Trial 1 (Ave.) 10 C
4 ppm
35% Sat.
Trial 2 (Ave.) 10 C
5 ppm
44% Sat.
Trial 3 (Ave.) 12 C
4 ppm
37% Sat.
10 Ft
Upstream
5 ppm
44% Sat.
4 ppm
35% Sat.
4 ppm
37% Sat.
10 ft
Downstream
8 ppm
71% Sat.
7 ppm
61% Sat.
8 ppm
74% Sat.
20 ft
Downstream
8 ppm
71% Sat.
8 ppm
71% Sat.
6 ppm
56% Sat.
Total Average
4.3 ppm
38.7% Sat.
7.7 ppm
68.7% Sat.
7.3 ppm
66% Sat.
4.3 ppm
38.7% Sat.
Conclusion: The oxygen levels downstream of the waterfall, are higher than upstream, as demonstrated
by the data above with the two average measurements upstream from the falls being 38.7% saturated and
downstream from the falls being 68.7% and 66.0% saturated. This is consistent with the concept that the
churning of the waterfall exposes more water to the air, thus increasing the ability of the water to absorb
atmospheric gases.
Field Study (B)
While on a class trip to the zoo, a group of students noticed the sea lions were bobbing up out of the
water. They began wondering if that was their common type of activity throughout the day or if it was
related to something else such as feeding schedule. They felt like this bobbing behavior was related to the
sea lions anticipating and looking for their food. The students conducted some background research on
sea lion behavior and thought that they should conduct some initial observation of the sea lions at the
Zoo. The students created an initial ethogram for Bronx Zoo Z. californianus. This tool helped better
inform the behavior choices and definitions of “activities” within their study. Then, on three separate
days, the students planned to observe the sea lions’ activity 70 minutes before feeding time and again 10
minutes before feeding time. They would observe the sea lions for 10 full minutes using instantaneous
sampling every minute. The behavior would be marked “NB” for not bobbing (not bringing their head
out of the water and looking around) or “B” for bobbing (bringing their head out of the water and looking
around). The students predicted that the sea lions would be bobbing more as feeding time approached, as
the sea lions were looking for their food.
Investigation Design
Title: The effect of proximity of feeding time on the bobbing behavior of sea lions.
Research Question: How does proximity to feeding time affect the bobbing behavior of sea lions?
Hypothesis: If sea lions are closer to their feeding time then their bobbing level will be greater than at
other times because the animals are anticipating getting food.
Independent Variable: Number of minutes prior to feeding time
Change in independent variable:
Number of repeated trials:
70 minutes before feeding time
10 minutes before feeding time
3 different days, 10 minutes per
day
3 different days, 10 minutes per
day
Dependent Variable: Bobbing behavior of the sea lions (not bobbing or bobbing as described above).
Constant Variables: location, species of animals, number of animals, time of day, season, intervals
(every 1 minute for 10 minutes).
Data:
The students also used the following system to record their bobbing activity:
NB (Not Bobbing): majority (more than 50% of the sea lions in the exhibit) were not bobbing.
B (Bobbing): majority (more than 50% of the sea lions in the exhibit) were bobbing.
28-May
Morning
70 Mins Prior 10 Mins Prior
1 NB
NB
2 NB
NB
3 NB
B
4 NB
B
5 NB
B
6 NB
B
7 NB
B
8 NB
B
9 NB
B
10 NB
B
Afternoon
70 Mins Prior 10 Mins Prior
NB
B
NB
B
NB
B
NB
NB
NB
B
NB
B
NB
B
NB
B
NB
B
NB
B
29-May
Morning
70 Mins Prior 10 Mins Prior
1 NB
NB
2 NB
NB
3 NB
B
4 NB
B
5 NB
B
6 NB
B
7 NB
B
8 NB
B
9 NB
B
10 NB
B
70 Mins Prior
NB
NB
NB
NB
NB
NB
NB
NB
NB
NB
Afternoon
10 Mins Prior
B
NB
NB
NB
B
B
B
B
B
B
1-Jun
Morning
Afternoon
70 Mins Prior 10 Mins Prior 70 Mins Prior 10 Mins Prior
1 NB
B
NB
B
2 NB
B
NB
B
3 NB
B
NB
B
4 NB
B
NB
B
5 NB
B
NB
B
6 NB
B
NB
B
7 NB
B
NB
B
8 NB
B
NB
B
9 NB
B
NB
B
10 NB
B
NB
B
Conclusion:
Sea lions at the Bronx Zoo change their behavior as their regular feeding time approaches. As observed
on each of three dates, within 10 minutes before both morning and afternoon feeding times, the sea lions
exhibited bobbing behavior. This behavior was not exhibited 70-60 minutes before feeding time.
Therefore sea lions in captivity seem to anticipate feeding time and alter their behavior as that feeding
time approaches. Is this a response to a stimulus or do the sea lions have a sense of time? We are not sure.
Further investigation might reveal which of these may be triggering the change in behavior.
Secondary Research
An Urban Advantage teacher had just completed a plate boundaries unit in which she introduced the IRIS
website which lets students search for earthquake data, map, graph and download it. After researching
plate boundaries of different types, a group of 8th graders approach their teacher and propose to
investigate the relationship between type of plate boundary and magnitude of earthquakes for their exit
project. The students hypothesize that earthquakes occurring at transform boundaries generally will be of
greater magnitude than earthquakes that occur at ridges (divergent plate boundaries), because when plates
are sliding past each other they would seem to store more mechanical energy than plates that are simply
diverging. The students determine the time frame for their study; they include only earthquakes for a 20
year period (from January 1, 1989 to December 31, 2008), and have identified one ridge and one
transform fault off the Pacific South American coast that they will compare for their project. Using the
IRIS web site, they set the search parameters to the settings described above, download the data, then
calculate and compare average Richter magnitudes for all the quakes at the transform boundary vs. the
divergent boundary (ridge).
Investigation Design
Title: The effect of plate boundary type on magnitude of earthquakes.
Research Question: How will the type of plate boundary affect the magnitude of earthquakes occurring
along that plate boundary?
Hypothesis: If an earthquake occurs at a transform plate boundary then its magnitude will be greater than
if it occurs at a divergent plate boundary because when plates are sliding past each other (transform) they
store more mechanical energy than plates that are simply diverging.
Independent Variable: Type of plate boundary
Change in independent variable:
Transform plate boundary
Divergent plate boundary
Number of repeated trials:
Number of earthquakes recorded
at 1 boundary in 20 years
Number of earthquakes recorded
at 1 boundary in 20 years
Dependent Variable: Magnitude of earthquakes (on the Richter Scale)
Constant Variables: Twenty years’ earthquakes per boundary type; all values taken from one database,
oceanic crust on both sides of each boundary. Plate boundaries are adjacent to each other to reduce
variation in other variables.
Data:
Transform
Divergent
Date
Magnitude
Date
10/24/07
4.4
5/16/07
5/7/07
Magnitude
3/22/08
5.6
4.7
7/28/07
4.4
5.4
12/12/04
4.9
6/15/05
5.6
9/19/04
4.2
3/12/05
4.6
3/29/04
4.3
1/9/03
4.9
12/31/03
3.7
12/23/02
4.3
6/3/03
4
8/4/02
5.6
6/3/03
4.4
7/18/02
5.3
5/31/03
4.3
4/6/02
4.6
5/20/03
4.9
3/11/02
5.2
3/18/02
4.8
2/22/02
4.4
3/15/02
3.9
1/29/02
4
1/25/02
3.9
7/28/01
4.2
10/23/01
4.6
6/30/01
4.4
9/10/01
4.8
5/26/01
4.7
5/25/01
4.1
2/19/01
5.1
4/20/01
4.6
12/31/00
4.5
12/23/00
4.3
8/1/99
3.7
2/6/00
4.7
7/12/99
4
5/9/99
4.6
3/20/99
4.9
5/19/98
5.1
3/9/99
4.5
8/26/97
4
12/24/98
4.4
3/18/97
4.2
11/6/98
4.5
10/5/96
5.2
1/19/98
4.6
1/22/91
4.7
10/25/97
4.1
9/13/89
4.9
3/5/96
4.2
11/17/95
5.3
8/25/93
5.6
7/1/93
5.2
11/20/91
5.3
2/13/01
5.2
2/21/89
5.3
Average earthquake magnitude at a transform plate boundary: 4.7 (for 33 earthquakes)
Average earthquake magnitude at a divergent plate boundary: 4.5 (for 26 earthquakes).
Conclusion:
Our hypothesis that plates that are moving past each other (transform boundary) store more mechanical
energy than those moving away from each other (divergent boundary) and therefore result in larger
earthquakes is not strongly supported by our observations. Our observations show a mixed result, at a
divergent plate boundary (ridge) we found an average magnitude of 4.5 on the Richter Scale for 26
earthquakes and an average of 4.7 on the Richter Scale for 33 earthquakes recorded on a near by
transform plate boundary over the same period of time. It should also be noted that the largest earthquakes
recorded at each plate boundary type had magnitudes of 5.6.
We conducted some research on line and ran across these two references:
“The crust may first bend and then, when the stress exceeds the strength of the rocks, [they] break and
"snap" to a new position. In the process of breaking, vibrations called "seismic waves" are generated.”
(http://pubs.usgs.gov/gip/earthq1/how.html 6/12/09 Maintained by John Watson and Kathie Watson
Last
modified 10-23-97 (jmw))
“… When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't
just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not
moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break,
the earthquake occurs.” (http://www.geo.mtu.edu/UPSeis/why.html, 6/12/09, This site is currently
maintained by: Kevin Endsley kaendsle@mt u.edu and Carol Asiala
<cj asiala@mtu.edu> For Dr. Wayne Penningt on, Dept. of Geological Engineering and
Sciences, Michi gan Technological Uni versit y)
Perhaps another way of looking at this situation is that at both of our chosen transform and divergent
boundaries we are looking at a boundary between two oceanic plates with the same type of rock. Perhaps
the more important factor related to the magnitude of an earthquake is not the speed at which, and the way
the plates are moving, but the materials that the plates are made of and the strength of those rocks. Since
properties like hardness are the same for all samples of a mineral, then perhaps the strength of samples of
the same rock are the same, and they break at the same point releasing similar amounts of energy in an
earthquake no matter how fast they reach that point of stored energy.