Scientific Methods Section 1.2 Objectives:

Identify steps that make up scientific methods

Explain how the meteorite impact hypothesis developed

Scientific Method Steps

Scientific Methods: organized, logical approaches to scientific research.

Suggested Steps: State the Problem Gather Information Form a Hypothesis Test the Hypothesis State a Conclusion

State the Problem Scientific inquiry often begins

as a result of observation. Observation: using the senses

of sight, touch, taste, hearing, and smell to gather information about the world.

Ask a question: How?, Why? To begin an investigation.

Ex: Why did the dinosaurs go extinct 65 million years ago?

Gather Information One important means of

gathering information is through measurement.

Measurement: involves the comparison of some aspect of an object or phenomenon with a standard unit, such as a meter, a Celsius degree, or a kilogram.

Units of Measure

Can you name some other units of measure?

Some Units of Measure Inch, foot, yard, mile, acre, light

year (9.5 trillion km) Millimeter, centimeter, meter,

kilometer, hectare Ounce, pound, ton, megaton Gram, kilogram, metric ton Degree Fahrenheit, degree Celsius Milliliter, liter

Accuracy and Precision Accuracy refers to how close

you are to being correct Precision involves the unit of

measure. Ex.: a distance measured in

millimeters is more precise than one measured in centimeters.

Dinosaur Extinction Information

Scientists approach for gathering information: Examined the fossil record for clues They studied rock layers from that

time period around the world They discovered that in certain

locations these layers contained iridium, a substance rare in earth rocks but common in meteorites.

They found that the rocks in these areas contained 160 times the normal amount of iridium in earth rocks

Form a Hypothesis

Hypothesis: a possible explanation or solution to the problem based on facts, which are often established through observation.

The Meteorite-Impact Hypothesis

The hypothesis: About 65 million years ago, a giant

meteorite crashed into the earth. The impact of the collision raised enough dust to block out the sun’s rays for many years. The earth probably became colder, plant life began to die, and many species, including the dinosaurs, became extinct. As the dust settled over the earth,it formed a layer of iridium rich rock.

Test the Hypothesis Once the hypothesis has been proposed,

it should be tested. The evidence should support it.

A hypothesis is tested through experimentation, a procedure carried out according to certain guidelines.

Experiments test variables, a factor in an experiment that can be changed.

An experiment set up to test a variable is called a controlled experiment.

Example of Controlled Exp.

A control is usually run in a controlled experiment to assure that only one variable is being tested. The control will have the same conditions as the experiment except for the variable.

To measure the effects of the amount of sunlight on plants, scientists could vary the amount of sunlight hitting a plant while having a control plant receive normal amounts of sunlight.

They would observe both plants and record their observations

What is the variable in this experiment?

Dinosaur Experiments Simulating an actual meteorite

impact in an experiment is impossible, making it difficult to prove the meteorite-impact hypothesis.

Computer models can be used to simulate a meteorite impact and the resulting aftermath.

Scientist found that the dust cloud resulting from the collision of a meteorite 10 km in diameter would have been sufficient to lower the earth’s temperature considerably.

Further Impact Evidence Further evidence was needed to prove

that the iridium found had come from a meteorite.

When the scientists examined the rock layers, they found strangely deformed quartz particles. These types of quartz particles were only found at meteorite impact sites, nuclear testing sites, and in moon rocks.

State a Conclusion

After many experiments and observation, scientists reach conclusions regarding the correctness of their hypothesis.

It may be : Accepted as stated Altered slightly Discarded altogether

Impact Hypothesis Conclusion

Fossil evidence does not prove that a meteorite was responsible for the extinction of the dinosaurs

The evidence does show that large amounts of meteorite dust reached the earth at the time of the extinction of the dinosaur

Until new evidence is found, this hypothesis can be used a possible cause of dinosaur extinction.

Observation Exercise I – Nature Area

Choose a partner Outside, make five (5)observations each

by smell, touch, sight, and hearing. (total of 20)

From your observations, state one problem (a questions to be answered)

Follow the steps in the scientific method to develop a conclusion to your problem

Max. 15 points

OBSERVATION #2

With partner make some observations on the rock outcrop at rear of A.I. High.

You may use the rock hammers and chisels to break away weathered surfaces to expose fresh surfaces for observation.

State one problem with the formation that you can not answer without some data collection and experimentation.

All observations and sample gathering notes should be written in your field notebooks (section off portion of notebooks).

FIELD GEOLOGISTS Geologists also study forces that act on the Earth and

things living there, such as landslides, volcanoes, and other natural occurrences.

A field geologist is someone who studies geology "in the field."

To become a field geologist, you should start studying physical and natural sciences in high school.

Working as a field geologist includes plenty of time outdoors, as might be expected.

Field geologists must take carefully monitored samples of rock material for testing and possible carbon dating.

TOOLS OF A FIELD GEOLOGIST

1. Field Notebook 2. Rock Hammer 3. Chisel 4. Brunton Compass

Geologist’s Field Notebook

ROCK HAMMER & CHISEL

ROCK HAMMER SAFETY 1. Wear goggles 2. Watch for flying bits of rock 3. NEVER TAKE YOUR EYE OFF

OF TARGET!!! 4. Small taps will suffice – NO

BIG BANGS!

BRUNTON COMPASS

USING A BRUNTON COMPASS The Pocket Transit may be adjusted for declination angle according

to one's location on the Earth. It is used to get directional degree measurements (azimuth) through use of the Earth's magnetic field. Holding the compass at waist-height, the user looks down into the mirror and lines up the target, needle, and guide line that is on the mirror. Once all three are lined up and the compass is level, the reading for that azimuth can be made. Arguably the most frequent use for the Brunton in the field is the calculation of the strike and dip of geological features (faults, contacts, foliation, sedimentary strata, etc.). If next to the feature, the strike is measured by leveling (with the bull's eye level) the compass along the plane being measured. Dip is taken by laying the side of the compass perpendicular to the strike measurement and rotating horizontal level until the bubble is stable and the reading has been made. If properly used and if field conditions allow, additional features of the compass allow users to measure such geological attributes from a distance.