Snail Races
Using the Scientific Method
and the Metric System
How Do Biologists Study Living Things?
Scientific Method
•Observation: objective notation of a phenomenon
•Hypothesis: question that can be tested by
experimentation
– Experiment
– Data Collection
– Conclusion
•Supported Hypothesis
•Theory: hypothesis supported by repeated testing
•Principle: theory supported over a long period of time
Today
• Observation
– Behavior of snail
– Anatomical description using microscope
• Hypothesis
– Are large or small snails faster?
– Are warm or cold snails faster?
Use BOTH eyes
Set at 1X to start
Use to increase image size
Adjust to focus
Turn light on
Put your snail here
(clean off later!)
Observations with a Dissecting Microscope
Metric System
A scientific measurement system where
quantities differ by factors of 10.
Length
Meter (m)
Weight
Gram (g)
Volume
Liter (l)
Centimeter (cm)
100 cm = 1 m
Millimeter (mm) Milligram
Milliliter (ml)
1000 mm = 1 m 1000 mg = 1 g 1000 ml = 1 liter
10 mm = 1 cm
Metric Measurements in Today’s Lab
Length
Ruler
Weight
Scale
Volume
Graduated
cylinder using
water
displacement
Grams and tenths
of a gram
Ex. 8.6 grams
Centimeter (cm)
and tenths of cm
Ex. 5.3 cm
Milliliter (ml)
Ex. 11 ml
Length Measurements
Length
Ruler
Centimeter (cm)
and tenths of cm
Ex. 5.3 cm
Weight Measurements
Weight
Scale
Grams and tenths
of a gram
Ex. 8.6 grams
Volume Measurements
Volume
Graduated cylinder
using water
displacement
Milliliter (ml)
Ex. 11 ml
Hint: Measure your snail’s volume after the
races to keep him/her moving at optimal speed!
Mathematics
• Average = sum of distances
number of measurements
• Significant figures
– Consistent with the smallest unit on the
measuring device
– Eg. 2.43 cm, should be reported as 2.4 cm
– Round up if next number is 5 or above
Graphing
6
5
4
Warm
Cold
3
2
1
0
Small
Medium
Snail Size
Large
Worksheet
• Complete pages 7-13 of Snail
Races Worksheet
• Be sure your instructor checks your
completed worksheet before you
leave the lab
CLEAN UP!
Make sure your lab station and the
surrounding benches look the same way
they did when you arrived!
CLEAN UP!
•
•
•
•
Return your snail to the aquarium
Empty and rinse graduated cylinders
Rinse and dry watch glasses
Leave glassware, rulers, string in a neat
arrangement at your station
• Clean your work area
• Clean microscope stage, cover and
return microscope to cabinet