Sci method, part 3

1. Life Science
Scientific Inquiry
Data Collection & Analysis

2. Bonus: What do IV and DV stand for and what are they?
- IV = independent variable (the thing you change to test its effect)
- DV = dependent variable (the result or thing that responds to the IV)
1. What is a scientific procedure?
• A detailed, step-by-step set of instructions for performing an experiment and
gathering data.
1. What type of units should you use for measuring the responding variable?
• Metric units (SI units such as millimeters, liters, seconds, grams, m/s, or Celsius)
1. True or False? You should try your best to collect subjective data in order to
eliminate bias in your experiment.
• False (objective data is less prone to experimenter bias)
1. What part of your hypothesis should describe the IV?
• The “IF…” phrase
1. Where/how should experiment results be recorded?
• In a data table (in your lab notebook, then transferred neatly to SI worksheet table)
• IV in left-hand column, DV across to the right, averaged values at far right column
In your lab notebook, please answer as best you can:
Week 29
Review Quiz

3. Data Collection
• As you perform the experiment, observations and
data must be recorded.
– measurements listed in a chart
– written observations
– drawings
– photos Soil Type
(Independent Variable)
Number of worms (per m2
, 3 cm deep)
(Dependent Variable)
Day 1 Day 2 Day 3 Day 4 Day 5 Average
Compost
Bark dust
Dirt with compost
Backyard dirt

4. Data Analysis
• Next, graph the data to show cause/effect
– Numbers, observations, and measurements are
broken down, organized, and studied
– Graphing the data allows patterns to emerge,
showing cause-and-effect relationships
• Independent Variable on the X-axis
• Dependent Variable on the Y-axis
– Label each axis
– Include units and a title

5. Qualitative vs Quantitative Data
• Does the IV describe a quality or quantity
of something?
– If it can be measured with numbers, then it is
quantitative. If not, then it’s qualitative.
• Incubator warmth
• Hours of sleep
• Surface texture
• Brand of soda
• Type of fruit
• Distance travelled
• Saltiness of water
Quantitative
Quantitative
Qualitative
Qualitative
Qualitative
Quantitative
Quantitative

6. Which Type of Graph?
• A quantitative IV
should use a line or
scatter plot graph.
• A qualitative IV
must use a bar
graph or pie chart.
The three sample in each group of the bar graph should be combined into average values.

7. Sample Line Graph

8. Scatter Plot
• Assign number values at even intervals.
– Divide largest value by the number of lines/boxes.
• Graph each data point.
• Draw a “best fit” line
through the points.
• What type of data does
this graph show?
- We can’t tell what the numbers mean because there are
no LABELS or UNITS!

9. Bar Graph
• What is the IV?
– Type of bread.
• What is the DV?
– Mold growth.
Pie Chart
• Shows parts of a whole
(not cause-and-effect).
– IV = Skittle color
– DV = How many per bag

10. Graphing Exercise
Hummingbird Preferences
Study Jams Video
What was the IV (manipulated variable)?
(birdfeeder color)
How was the IV changed?
(4 different colors of birdfeeders were tested)
What was the DV (responding variable)?
(amount of food eaten)
How was the DV measured?
(by taking pictures of the feeders each day)
How many trials did Mia perform?
(seven days = 7 trials)
What type of data was collected?
(subjective)
What type of graph should Mia use to show her results?
(there is no numerical data, it cannot be graphed)

11. Graphing Objective/Qualitative Data
Hummingbird Syrup Missing from Feeder at end of day (ml)
Sept 8 Sept 9 Sept 10 Sept 11 Sept 12 Sept 13 Sept 14 Average
Red 350 227 412 448 325 276 365 343 ml
Blue 22 7 15 19 8 15 10 14 ml
Green 11 9 7 5 12 5 10 8 ml
Yellow 30 45 67 69 69 72 33 55 ml
What type of graph should be used to display these results?
(a bar graph)

12. AverageSyrupEatenEachDay(ml)

13. Experiment 29
Can Eggs Float?

14. EXPERIMENT 29 - Observation
In your lab notebook, write our question (what we
are curious about or the problem/objective):
Can an egg float in water?
What do we already know? (write this down, too!)
• Normally, eggs don't float in water.
– Have you ever boiled eggs on the stove?
• People float easier in the Great Salt Lake than in swimming pools.
• Boiled eggs might be denser than raw eggs.
What did we learn after researching the topic?
• Salt doesn't disappear, it disassociates (separates and fits
between H2O molecules) in water.
This is the "look
around" or "make
observations" step.

15. EXPERIMENT 29 - Hypothesis
Write down your hypothesis:
• What do you think will happen?
– This should answer your "question" formed in the
OBSERVATION step of the scientific method.
If we dissolve enough salt in water,
then an egg will ____________________
because ____________________.

16. EXPERIMENT 29 - Experiment
Materials:
• A tall glass
• Graduated cylinder or
beaker
• An egg
• A measuring spoon
• A spoon for stirring
• Water
• Salt
• Paper towels
Procedure: (from ECGS pg. 60)
• Fill a cup with 300 ml of water.
• Drop an egg (carefully) into the cup of water. Record
whether it sinks or floats in your laboratory notebook.
• Use the spoon you have for stirring to pull the egg back
out of the glass. **Let it drip in the glass so that you do
not lose too much water.
• Add 5 ml of salt to the water and stir with your stirring
spoon until the salt is dissolved.
• Set the egg (carefully) into the cup of water. Write
down any difference between how the egg behaved
before and how it behaves this time.
• Repeat steps (C) - (E) a total of 6 times. Each time, note
the difference (in your laboratory notebook) how the
egg behaves. If the egg's behavior does not change
even after you have repeated steps (C) - (E) 6 times,
continue to repeat the steps until you see a difference.
• Clean everything up and put it all away.

17. EXPERIMENT 29 - Data Collection
In your lab books, make a chart like this:
Water Salt (ml) Float or Sink Observations
Trial #1
Trial #2
Trial #3
Trial #4
Trial #5
Trial #6
Trial #7
Trial #8

18. EXPERIMENT 29 – Raw Data
Let's analyze the data: This is a
great way to
organize
your data.
Water Salt (ml) Float or Sink Observations
300 ml 0 Sink (2cm) Egg sank down quickly - had to
use spoon to keep from cracking
300 ml 5 Sink (2cm) No difference in egg, water looks
a little cloudy
300 ml 10 Sink (2cm) Sank down slower
300 ml 15 Sink (2cm)
300 ml 20 Sink (6cm) Sort of bobbed around a little
before sinking halfway down
295 ml 25 Float (12 cm) Sank down halfway, then came
to top
290 ml 30 Float (12 cm) Stayed at top, water so murky we
can barely see the egg
280 ml 35 Float (12 cm) Part of the egg floated above the
surface of the water
Look for
patterns,
trends, or
correlations.
Compare
multiple trials
and consider
throwing out
crazy data.

19. EXPERIMENT 29 – Data Analysis
Let's analyze the data: Visual
record of
the data
Patterns,
trends,
correlations,
and erroneous
data are easy to
spot on a graph.
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30 35
EggFlotation
Salt (ml) in 300 ml water

20. EXPERIMENT 29 - Conclusion
Does the data support your hypothesis?
Based on the data we collected, our eggs floated
when at least ____ ml of salt were added to 300ml
tap water.
Write your conclusion:
This supports our hypothesis that if we add enough
salt to water, an egg can float because...
Then SHARE your findings:
Report to the class what you discovered through oral
presentation and/or written report.
Include modifications & sources of error:
Egg “floatiness” could be measured by distance from bottom.