module. what is science? scientia = knowledge “process that uses observations and investigations...

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What is Science?

Scientia = knowledge

“Process that uses observations and investigations to gain information about events in nature.”

Categories of Science

Life Science

Earth Science

Physical Science

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What is the scientific method? – organized set of investigating procedures

State the problem

Gather information

Form a hypothesis

Test hypothesis

Analyze data

Draw conclusions

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This could be a question about an observed problem or curiosity.Researching aspects of the problem to understand it.A possible explanation for a problem – this may be right or it may be wrong.Develop an experiment to try to prove or disprove your hypothesis.

The data will either support or not support your hypothesis. The data speaks for itself and should be viewed without prejudice

The conclusion should refer to the data as either the validation of or the contradiction to your hypothesis.

It is never wrong to have a wrong hypothesis. Your conclusions should simply either support or not support you hypothesis.

What are variables?

Variables are quantities or values which can have more than one number.

What are the two kinds of variables?Dependent variables – This is the responding variable – the variable that is measured by the experimenter

Independent variable – This is the manipulated variable – the variable which is controlled and changed by the experimenter.

The expression DRY MIX can help you remember and understand the difference between the two.

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D

R

Y

M

I

X

D

-- Dependent Variable-- Responding Variable (measured)

R

-- Y Axis

M-- Manipulated variable (controlled)

I

-- Independent Variable (controlled)X -- X - Axis

D

R

Y

M

I

X

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What are Constants in an experiment?

A Constant or Constant Variable is a variable which does not change during the course of the experiment

Example: During an experiment which measures the effect of temperature on plant growth, the constants might be soil type, plant type, amount of sunlight, amount of water. All variables in an experiment should be held constant except the experimental variables (dependent and independent)

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What is a control in an experiment?

A control is a standard for comparison in an experiment.

For example, in an experiment which measures the effect of temperature on plant growth, a plant at room temperature is used to compare other plants at various temperatures. The control is the basis for comparison of changes which take place in the dependent (responding) variables.

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What is an observation?

In science an observation is information collected by the senses – all of the sense – not just visual. That information is often called data.

There are two types of data: Qualitative data is information that is descriptive which does not involve measurements.

Quantitative data are observations in the form of measurements.

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What are models and how are they used in science?

A model is something which represents a concept which is either very small (the atom), very large (the solar system), or difficult to access the real thing (an eyeball).

Models help students to better understand concepts and relationships.

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What is the difference between a hypothesis, theory, and law?

A hypothesis is a possible answer to science question? Hypotheses may be right or wrong – they give the experimenter a basis to prove or disprove.

A theory is an explanation of a thing or event based on knowledge gained from experiments or investigations.

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A scientific law is a rule of nature which seems to be always true.

The law of gravity

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What is a measurement standard?

A measurement standard is an agreed-upon exact quantity for measuring.

What is a unit?

A unit is measurement quantity used to describe a measurement value. UNITS ARE IMPORTANT. A measurement contains a number and a unit. The number is the adjective and the unit is the noun. The number describes (modifies) the unit.

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Example – This morning I awakened early and ran five before breakfast.Five what ? 5 miles, 5 minutes, 5 meters, 5 secs, 5 feet. Numbers in a measurement are MEANINGLESS without units.

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The Metric System – Base units & SI Prefixes

You must know these

And all of these prefixes

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LengthSI unit of length is the meter

Definition - distance light travels in a vacuum in 1/299,792,458 of a second.

A meter is about the distance from the floor to a doorknob. Measurements smaller than a meter are usually centimeters. Longer distances are usually in kilometers.

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Mass - amount of matter in an object

SI Unit is the kilogram.

Standard is a palladium-iridium cylinder kept in France.One liter of water has a mass of 1 kilogram.

A paper clip has a mass of about a gram. Smaller mass quantities are measured in milligrams.

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Time - Second

1/60th of a minute

Also defined by the number of vibrations of a Cesium-133 atom.

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Units of Temperature – Temperature simply measures how hot or cold something is

In science temperature is measured in degrees Celsius (oC).

In daily life temperature is measured in degrees Fahrenheit (oF). (For example, The high temperature for today is 82 oF or body temperature is 98.6 oF)

Converting between oF and oC:

oC = 5/9(oF – 32)

oF = 9/5oC + 32

Practice: 98.6oF = ___ oC

oC = 5/9 (98.6 – 32) = 37oC

Temperature conversions practice:

Convert -12oC to oF

oF = 9/5 (-12) + 32 = 10.4 oF

Kelvin Temperature Scale – A third temperature scale used to perform temperature calculations.

oC and oF temperatures do not show proportional relationships and are rarely used in calculations because they have zero and negative values. Kelvin is related to oC in the following way:

K = oC + 273 Practice: 200oC = ____K73

Derived Units - units which get their meaning from other unitsVolume - amount of space an object occupies. Volume is derived from units of length.

1 Liter is equal to 1 dm3 or 1000 cm3

10 cm

10 cm

10 cm

1 dm = 10 cm

Density - A Derived UnitDensity is derived from units of mass and volume and refers to the overall “lightness” or “heaviness” of a substance.

mass volume

Density = or d = m vThe density of water is 1.00 grams/cm3 . Objects

with a density less than 1 gram/cm3 will generally float in water and objects with a density greater than 1.00 grams/cm3 will generally sink in water.

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Units of Measurement in Calculations. Conversion Factors

Definition - a problem-solving method based upon treating units in calculations as if they are algebraic factors.

Unit Conversions (or conversion factors) are

•a fraction with units

•equal to a value of ONE

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Using a Conversion FactorHow many hours are in 1 Week?

What is your unknown? hours

What is your known? 1 Week

Find numerical relationships which link your known to your unknown.

1 wk = 7 days 1 day = 24 hours

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Solving Problems

Start with your known

1 Week

Multiply by conversion factors which cancel the unit

X7 Days 1 Week-------

------- X 24 hours 1 day

------

----

Cancel the units, leaving the units to the unknown.

= 168 hrs

Solve the problem.

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What are Significant Figures?

Definition - The number of digits in a measurement known to be exact, plus the last digit which is estimated. This will show you why 5 X 5 25

Significant Figures relates directly to accuracy.

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Significant Figures Rules•Nonzero Digits are significant. 677.3 mm = 4SF

•All zeros between nonzero digits are significant. 7.003 grams = 4SF

•Zeros which begin a number containing a decimal are NOT significant. 0.00045 mL = 2SF

•All zeros which end a number containing a decimal point are significant. 1.00 meters = 3SF

•Zeros ending a number with no decimal point are questionable and are assumed insignificant. 40,000 people = 1SF

Practice Problems7.70 grams 3sf

0.0050 meters 2sf

612,000 microbes 3sf

5.000 km 4sf

50070 mm 4sf

6.020 X 1012 atoms 4sf

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Calculations involving Sig Figs

Addition and Subtraction

When adding or subtracting measurements, the final answer may have no more digits to the right of the decimal point than the measurement with the fewer number of digits to the right of the decimal point.

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Addition and Subtraction Examples

4.12 grams + 4.2 grams

8.32 grams

2 digits to the right of decimal

1 digit to the right of decimalAnswer limited to 1 digit to the right of the decimal

/

8.3 grams Correct answer

53.787 meters - 7.32 meters46.467 meters

3 digits to the right of decimal2 digits to the right of decimal

Answer limited to two digits to the right of the decimal

/

Since the number rounded off is 5 or greater the last digit is rounded up one. Answer 46.47 meters

Multiplication and Division

The answer to a multiplication or division problem may have no more significant figures than the measurement with the fewer (or fewest) number of significant figures.

33.67 mm x 6.26 mm = 210.7742 mm 2

CALCULATOR GIVES THE WRONG ANSWER!!

Remember that an answer may be no more accurate than the least accurate measurement.

4sf 3sf Calculator gives answer with 7 sf

Round answer off to three sf.

// //

Correct answer 211 mm2

Calculations involving Significant Figures

5 m X 5m = 25 m2/ NOT

Major Concept: An answer to a calculation may be no more accurate that the least accurate measurement

5 m X 5m = 25 m2

1sf 1sf 2sf

Accurate Measurements are important

5.0 m X 5.0 m = 25 m2

More accurate measurements

Honest, accurate calculation

Density Calculations

What is the density of a metal with a mass of 43.6 grams and a volume of 3.77 cm3?

Density =volume

mass377.3

6.43

cm

g

Calculator answer is 11.56498674 g/cm3

WRONG ANSWER

3 sig figs

3 sig figs

Answer should only have 3 sig figs

Correct rounded answer = 11.6 g/cm3

Scientific Notation

One number with two parts, used for three reasons:

•To represent very large numbers

•To represent very small numbers

•To clarify accuracy

First part of the number is the coefficient

6.023 X

The second part is the base ten exponent.

1023 One number with two parts

A graph is a visual display of data or information. In science data is collected and displayed in a manner to be easily understood and interpreted.

This is a bar graph

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This is a pie graph or circle graph. It is used to show parts of a whole. The sum of all parts is equal to 100%

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time (min)

This is a line graph. It shows relationships between two variables. In this example the variables are temperature and time. Temperature is the dependent variable and time is the independent variable.

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Practice Questions

• The next series of slides will give you some practice questions to prepare you for the end of course test.

• Answers are provided after each question slide. Make sure you think about these carefully.

• Please email with questions regarding any questions you do not understand.

A regional manager is concerned about the number of employee accidents occurring at his ten service centers. She makes a hypothesis that safety advertising will reduce accidents. She decides to test the hypothesis in her service centers. Each service center will use different number of safety posters to see if the number of accidents will reduce. Each service center manager will keep a record of the employee accidents reported.

How is safety advertising measured in this study?

a.number of employee accidents reported to the service center manager

b.number of service centers involved

c. number of safety posters in each service center

d.number of accidents in the service center


How is safety advertising measured in this study?

a.number of employee accidents reported to the service center manager

b.number of service centers involved

c.number of safety posters in each service center

d.number of accidents in the service center


How are the employee accidents measured in this study?

a. number of employee accidents reported to the service center manager

b. number of service centers involved

c. number of safety posters in each service center

d. number of accidents in each service center

Jasmine has been launching water rockets. She can vary the amount of water in the rocket and the launching angle of the rocket. She can also change the weight of the rocket by adding sand to the nose cone. She is curious about the factors which affect of the height to which the rocket will rise.

Which of the following is a hypothesis she could test?

a. Rockets using warm water will rise higher than rockets with cold water.

b. Rockets using five tail fins will rise higher than rockets with four tail fins.

c. Rockets with a pointed nose cone will rise higher than rockets with a rounded nose cone.

d. Rockets using more water will rise higher than rockets with less water.

The monthly heating bill for the Smiths is higher than all their neighbors. They formulate hypotheses about factors that affect their heating bill. Which of the following statements is NOT a hypothesis which they could test?

a. The greater the number of trees around the house, the lower the heating bill.

b. The fewer number of doors and windows in a house the lower the heating bill.

c. The larger the house the larger the heating bill.

d. The higher the heating bill, the more likely a family will seek cheaper heating methods.

A high school environmental science class studies factors that might affect pollution in the Reedy River. They discover that possible factors may include fertilizers, sewage, and trash from a landfill. Chemicals in that portion of the river are not a problem because there are no chemical plants upstream.

Which of the following is a testable hypothesis?

a. The more fertilizer in the river, the more crops will grow along the river.

b. The more chemical plants there are, the more chemical pollution that results.

c. The more trash sent to the landfill, the higher the income of families in the region.

d. The more sewage in the river, the greater the level of pollution.

Chickens lay varying numbers of eggs depending upon several factors. Which of the following is NOT a suitable testable hypothesis for a study of these factors?

a. Chickens exposed to more hours of light will lay more eggs.

b. Chickens which produce more eggs seem to lose weight.

c. Chickens in larger cages produce more eggs.

d. Chickens with more protein in their feed produce more eggs.

Henry was curious to see how light affects the growth of bread mold. He grew bread mold in fifteen identical containers containing the same amount and type of nutrients. Five containers were kept in total darkness, five were kept in half darkness and half light, and five were in a continually lighted condition. At the end of four days the containers were examined and the growth of the mold was measured and recorded.

Which of the following is Henry’s hypothesis?

a. The type of nutrient used will vary the amount of bread mold.

b. The more light withheld from the bread mold, the greater the amount of bread mold.

c. The amount of nutrient used will vary the amount of bread mold.

d. The greater the number of containers, the greater the amount of bread mold.


Which of the following is the controlled variable?

a. the amount of light exposed to the containers

b. the style of container used

c. the temperature of the bread mold

d. the quantity of bread mold


Which of the following is the dependent or responding variable?

a. the growth of the bread mold

b. the quantity of nutrient in each container

c. the amount of light exposed to each of the containers

d. the number of containers used.


Which is the independent or manipulated variable?

a. the amount of light exposed to each of the containers

b. the quantity of nutrient in each container

c. the growth of the bread mold

d. the number of containers for each experimental area

John wanted to find out which type of toothpaste was best at fighting bacteria. On an agar plate inoculated with bacteria, he placed 1 cm. of three different types of toothpaste. What is the dependent variable in John’s experiment?

a. the amount of bacterial growth

b. the different kinds of toothpaste

c. the types of bacteria

d. the amount of toothpaste

Shawn wonders about the things that may affect the time it takes ice cubes to melt. He formulates a hypothesis that the shape of the ice cube affects the time it takes to melt ice cubes. Shawn believes that the size of the ice cubes and the temperature of the environment are factors which may also affect the time it takes ice cubes to melt.

Which of the following would be the BEST method Shawn could use to test his hypothesis?

a. Use five ice cubes of the same shape and size. Use five identical containers of the same temperature. Measure the time it takes each cube to melt.

b. Use five ice cubes of the same shape and each having a different size. Use five identical containers of the same temperature. Measure the time it takes each cube to melt.

c. Use five ice cubes of the same size, but each having a different shape. Use five containers of the same temperature. Measure the time it takes each cube to melt.

d. Use five ice cubes of the same size, but each having a different shape. Use five containers, each at a different temperature. Measure the time it takes each cube to melt.

Thomas wanted to test the hypothesis that the higher the temperature of the water, the faster the sugar would dissolve.

Which of the following would BEST test his hypothesis?

a. Use four beakers of water: Beaker #1 at 20oC, Beaker #2 at 40oC, Beaker #3 at 60oC, and Beaker #4 at 80oC. Add one teaspoon of sugar to each beaker and measure the time it takes to dissolve.

b. Use two beakers of water: Beaker #1 at 20oC, Beaker #2 at 30oC. Add one teaspoon of sugar to each beaker and measure the time it takes to dissolve.

c. Use three beakers of water, all at the same temperature. Add one teaspoon of sugar to each beaker. Heat Beaker #1 over low heat. Heat Beaker #2 over high heat. Allow Beaker #3 to remain at room temperature unheated. Measure the time it takes for each to dissolve.

d. Use four beakers of water: Add 1 teaspoon of sugar to Beaker #1. Add 2 teaspoons of sugar to Beaker #2. Add 3 teaspoons to Beaker #3. Add 4 teaspoons of sugar to Beaker #4. Measure the time it takes for each to dissolve.

module. what is science? scientia = knowledge “process that uses observations and investigations...

Documents

module slide

constant variable

manipulated variable

independent module

dependent variables

variable measured r

data draw conclusions

hypothesis test hypothesis