Study Guide- Experimental Design

What is a Scientific Theory? A well tested hypothesis that is true in most cases.

Metrics Units to: Measure distance. METER Measure how heavy something is: GRAMS How much liquid is there in a container: LITERS Measure if an object will float or not: GR/ML The relation between force of gravity and the mass of an object. NEWTONS Measure the heat in an object. CELSIUS

Making conversions King Henry Died By drinking chocolate milk __ __ micro ___ ____ nano When do you move the decimal point to the left? –WHEN YOU GO FROM SMALL TO BIG NUMBERS. When do you move the decimal point to the right? –WHEN YOU GO FROM BIG NUMBERS TO SMALL NUMBERS.

Instruments What do you use to measure mass? –A TRIPLE BEAM BALANCE OR ELECTRONIC BALANCE What do you use to measure volume? –A GRADUATED CYLINDER What do you use to measure distance? –A RULER OR METER STICK What do you use to measure density? –A BALANCE AND A GRADUATED CYLINDER

Tables Where do you put the IV? IN THE LEFT COLUMN Where do you put the DV? YOU PUT THE DV LABEL ON THE TOP OF THE TABLE, AND THE DV DATA IN THE MIDDLE COLUMS IN THE TABLE Where do you put the levels of the IV? UNDER THE IV LABEL IN THE LEFT COLUMN

This student is studying three types of fertilizer with 5 plants of the same kind. He measures the plants once after 2 weeks of applying the fertilizer. Type of fertilizer Growth of plants Plant 1 Plant 2 Plant 3 Plant 4 Plant 5 MeanData range No fertilizer (control) Type 1 Type 2 Type 3

Types of graphs When do you use: Bar graph? WHEN COMPARING CATEGORIES WITH NUMBERS Pie graph? WHEN COMPARING CATEGORIES IN % OR PROPORTIONS Line graph? WHEN COMPARING NUMBERS WITH NUMBERS Double bar graph? WHEN COMPARING DOUBLE CATEGORIES

What kind of graph? This student is studying three types of fertilizer with 5 plants of the same kind. He measures the plants only once after 2 weeks of applying the fertilizer. IT IS A BAR GRAPH. IV IN THE X AXIS DV IN THE Y AXIS

Graphing When you have many trials, what do you do to summarize the data and graph? –YOU USE THE MEAN What does the data range tell you? –VARIATION WITHIN A LEVEL OF THE VARIABLE.

Type of data Qualitative –WHEN YOU ARE USING ATRIBUTES OR WORDS. Quantitative –WHEN YOU ARE USING NUMBERS

Steps to the scientific method O_______ OBSERVE Pose a _______________ QUESTION Go to the __LIBRARY________ and get ________ DATA Make a ______________ HYPOTHESIS Design an ________________ EXPERIMENT Test your ___HYPOTHESIS________ (collect _DATA____) Analyze the __________ DATA Make ________________ CONCLUSION Comm________________ COMMUNICATE

Where do scientists most commonly communicate their results? IN SCIENTIFIC JOURNALS

Parts of an experiment IV: WHAT YOU CHANGE ON PURPOSE IN ONE EXPERIMENT DV: THE DATA YOU COLLECT. Control: THE PART OF THE EXPERIMENT WITHOUT THE IV. Levels of the IV: CATEGORIES OF THE IV Constants: ANYTHING THAT STAYS THE SAME IN AN EXPERIMENT Sources of error: HUMAN OR INSTRUMENTAL ERRORS IN AN EXPERIMENT

See answers in the next slide Rodrigo wants to investigate which brand of shampoo makes more suds. He obtained 9 test tubes and wanted to make 3 trials per type of shampoo. He added 10 ml of warm water and a drop of shampoo A to the first 3 test tubes. He added 15 ml of cold water and a drop of shampoo B to the second set of 3 test tubes. Finally he added 20 ml of hot water and a drop of shampoo C to the third set of test tubes. He shook each test tubes 30 times and measured the height of the foam in each test tube.

Needs to keep the same temperature of the water Needs to keep the same amount of water Needs to measure instead of using drops. IV: type of shampoo DV: amount of suds Levels of the IV: Three types of shampoo Control: The old shampoo he has always used. Constants: Same temperature, same amount of water, same test tube, etc, etc.