Chapter one Notes

Weight: Gravitational attraction, Measured in newtons (N) (Kg X 9.8 = N) 50 Kg = 500 N
Mass: Amount of matter, measured in kilograms (kg)
Matter: Anything that has mass and takes up space, Is air matter? How do you prove it  (beaker, wad of paper)
volume: Amount of space, measured in Liters (L) or cubic centimeters (cm³)

Density: Ratio of mass/volume (Candle Experiment)
Density of water: 1 g/mL
Density is an intensive property, does not depend on the size of the piece!!

What is the purpose of science?

1.) Describe our world
2.) Explain/predict our world
3.) Modify our world

Steps of the scientific method

1.) Form a Question (Scientist and researchers try to form questions that are related to the above three statements.  You can form a question about anything and then you use specific steps to try and solve it)

Example: What is the effect of temperature on leaf color?

2.) Form a hypothesis. A hypothesis must be testable.  Always try and put your hypothesis in an if-then statement. For example:

In the fall if leaf color  change (dependent) is related to temperature (independent) , then exposing plants to low temperatures (treatment) will result in changes in leaf color (prediction).

3.) Explain how you will know if your hypothesis is correct.

Hess's balloon experiment and cosmic rays

4.) Experiment.  Set-up the proper experiment to test your hypothesis.  You experiment must be set up so that it will either prove or disprove your hypothesis.

5.) Conclusions: For an answer to your question based on your experimental findings.

What makes "Good" Science?

1.) The question is testable

2.) The results are repeatable

3.) The results are quantitative. (you have numbers to support your experiment)

Observations and Inferences (candle in the wind demonstration)

1.) An observation is something that a person can see, touch, taste, etc. 

examples: The grass is brown, The table is 36 inches long, Her hair is black

2.) An inference is something that a person concludes from an observation.

examples: The grass is brown because it did not rain (could the grass be brown for some other reason?), It must have rained because their is a puddle of water on the driveway.

Parts of an Experiment

1.) Independent variable: This is the variable that is being tested or controlled by the experimenter.  It is what is different about the two experimental setups. Sometimes known as the treatment!

2.) Dependent variable: How will you tell if there is a difference in the experiment.  This is usually a measured variable.

3.) Constants: Are the same for all parts of the experiment

4.) Control: This is the part of the experiment or group that does not get a "treatment" It is not found in all experiments only if there is a "treatment" being applied.  It is very important as without a control you can never be sure that the results are due to the "treatment"  The treatment can be a certain drug, amount of light, etc.

Blind study: Neither group knows who is getting the real treatment

Double blind study: Neither the group or researcher knows who is getting the real treatment.

Placebo:  This is a fake pill given to the control group.  For example if you are trying to test the effects of a drug on cholesterol levels you would give one group the real drug and one group a harmless fake drug.  You do not want a person to know if they are getting the real pill or the fake pill.  Many people feel that just by taking a pill they will get better.  This is called the placebo effect and it is very powerful.

Data: Actual qualitative or quantitative measurements taken in the the experiment. Do not get this confused with the conclusion. The conclusion uses the data to determine what happened in the experiment. 

Below you have a couple of experiments that can try to find the parts of an experiment.

Experiment 1

A person goes to Mensch's greenhouse and buys twelve tomato plants.   They plant the tomato's in the same soil and they all get the same amount of light and water.  6 of the plants get a nitrogen fertilizer and 6 plants get no fertilizer. At the end of 12 weeks the person measures the height of the tomato plants. The tomatoes which received the fertilizer are on average 5 inches taller than the plants that received no fertilizer. 

a.) Independent variable______________________

b.) Dependent variable_______________________

c.) Name 3 constants________________________

d.) Was there any data collected?__________

e.) Control _______________________________

f.) Was this a good experimental set-up?  If not what would you do differently and how would it help to strengthen the experiment?

Experiment 2

A person buys 100 identical fish. They put 50 fish in regular water, and 50 fish in some water that contains salt.  The fish get the same amount of food and light.  If a fish dies it is removed from the tank.  At the end of 2 weeks the number of live fish are counted in each tank.  Find the

a.) Independent variable______________________

b.) Dependent variable_______________________

c.) Name 3 constants________________________

d.) Control _______________________________

e.) Was this a good experimental set-up?  If not what would you do differently and how would it help to strengthen the experiment?

Experiment 3

An experimenter gets a group of 25 people.  The people take 1000 mg of vitamin C everyday for one year.  At the end of this time the experimenter records how many colds each of the people had. Find the

a.) Independent variable______________________

b.) Dependent variable_______________________

c.) Name 3 constants________________________

d.) Control _______________________________

e.) Was this a good experimental set-up?  If not what would you do differently and how would it help to strengthen the experiment?