Snail Races Snail Races

Using the Scientific Method Using the Scientific Method and the Metric Systemand the Metric System

How Do Biologists Study Living Things?How Do Biologists Study Living Things? Scientific MethodScientific Method

•Observation: Observation: objective notation of a phenomenonobjective notation of a phenomenon

•Hypothesis: Hypothesis: question that can be tested by question that can be tested by experimentationexperimentation

– ExperimentExperiment– Data CollectionData Collection– ConclusionConclusion

•Supported HypothesisSupported Hypothesis•Theory: Theory: hypothesis supported by repeated testing hypothesis supported by repeated testing

•Principle: Principle: theory supported over a long period of timetheory supported over a long period of time

TodayToday

• ObservationObservation– Behavior of snail Behavior of snail – Anatomical description using microscopeAnatomical description using microscope

• HypothesisHypothesis– Are large or small snails faster?Are large or small snails faster?– Are warm or cold snails faster? Are warm or cold snails faster?

Put your snail here(clean off later!)

Adjust to focus

Use BOTH eyes

Set at 1X to startUse to increase image size

Turn light on

Observations with a Dissecting Microscope

Metric SystemMetric System

LengthLength WeightWeight VolumeVolumeMeter (m)Meter (m) Gram (g)Gram (g) Liter (l)Liter (l)

Centimeter (cm) Centimeter (cm)

100 cm = 1 m100 cm = 1 m

Millimeter (mm)Millimeter (mm)1000 mm = 1 m1000 mm = 1 m

10 mm = 1 cm10 mm = 1 cm

MilligramMilligram1000 mg = 1 g1000 mg = 1 g

Milliliter (ml)Milliliter (ml)

1000 ml = 1 liter1000 ml = 1 liter

A scientific measurement system where A scientific measurement system where quantities differ by factors of 10.quantities differ by factors of 10.

Metric Measurements in Today’s LabMetric Measurements in Today’s Lab

LengthLength WeightWeight VolumeVolumeRulerRuler ScaleScale Graduated Graduated

cylinder using cylinder using water water displacementdisplacement

Grams and tenths Grams and tenths of a gramof a gram

Ex. 8.6 gramsEx. 8.6 grams

Centimeter (cm) Centimeter (cm) and tenths of cmand tenths of cm

Ex. 5.3 cmEx. 5.3 cm

Milliliter (ml)Milliliter (ml)

Ex. 11 mlEx. 11 ml

Length MeasurementsLength Measurements

LengthLengthRulerRuler

Centimeter (cm) Centimeter (cm) and tenths of cmand tenths of cm

Ex. 5.3 cmEx. 5.3 cm

Weight MeasurementsWeight Measurements

WeightWeight

ScaleScale

Grams and tenths Grams and tenths of a gramof a gram

Ex. 8.6 gramsEx. 8.6 grams

Volume MeasurementsVolume Measurements

VolumeVolumeGraduated cylinder Graduated cylinder using water using water displacementdisplacement

Milliliter (ml)Milliliter (ml)

Ex. 11 mlEx. 11 ml

Hint: Measure your snail’s volume after the Hint: Measure your snail’s volume after the races to keep him/her moving at optimal speed!races to keep him/her moving at optimal speed!

MathematicsMathematics

• Average = Average = sum of distancessum of distances

number of measurementsnumber of measurements

• Significant figuresSignificant figures– Consistent with the smallest unit on the Consistent with the smallest unit on the

measuring devicemeasuring device– Eg. 2.43 cm, should be reported as 2.4 cmEg. 2.43 cm, should be reported as 2.4 cm– Round up if next number is 5 or aboveRound up if next number is 5 or above

GraphingGraphing

0

1

2

3

4

5

6

Small Medium Large

Warm

Cold

Ave

rage

Spe

ed (

cm/m

in)

Snail Size

Worksheet Worksheet

• Complete pages 7-13 from lab Complete pages 7-13 from lab manualmanual

• Be sure your instructor checks your Be sure your instructor checks your completed worksheet before you completed worksheet before you leave the lableave the lab

CLEAN UP!CLEAN UP!

Make sure your lab station and the Make sure your lab station and the surrounding benches look the same way surrounding benches look the same way

they did when you arrived!they did when you arrived!

CLEAN UP!CLEAN UP!

• Return your snail to the aquariumReturn your snail to the aquarium• Empty and rinse graduated cylindersEmpty and rinse graduated cylinders• Rinse and dry watch glassesRinse and dry watch glasses• Leave glassware, rulers, string in a neat Leave glassware, rulers, string in a neat

arrangement at your stationarrangement at your station• Clean your work areaClean your work area• Clean microscope stage, cover and Clean microscope stage, cover and

return microscope to cabinetreturn microscope to cabinet