Today’s Schedule (Day F) 8:03 – 9:23 Testing 9:26 – 9:56 Period 1 9:59 – 10:32 Period 2 10: :08 Period 3 11: :44 Period 4 11:47 – 12:20 Period 5 12:23 – 12:56 Period 6 12:59 – 1:32 Period 7 1:35 – 2:09 Period 8 2:12 – 2:45 Period 9

Friday, September 19 (Day F) Objective: S8.A.2 Learn the Processes, Procedures and Tools of Scientific Investigations  Quiz  Finish Survey Research Projects  Don’t Forget Homework: MySkillsTutor.com Bar Graphs  Test next Thursday  Take Makeup quizzes & review for quiz tomorrow  Tomorrow: make-up quizzes

Does Temperature Affect the Rate of Bacterial Reproduction? No, the data in the table do not support the student’s hypothesis because bacterial reproduction increases as the temperature increases only at temperatures below 30.5  C. At temperatures greater than 30.5  C, the bacterial reproduction rate decreases as the temperature increases.

Does Temperature Affect the Rate of Bacterial Reproduction? This bacteria has a maximum reproduction rate at a single temperature near 30.5  C.

Does Temperature Affect the Rate of Bacterial Reproduction? Any one of the following factors could affect the reproduction rate of the bacteria: the type of nutrient medium used, the moisture level of the nutrient medium, the presence or absence of light, the type of bacteria used, whether or not the Petri plates were sealed, whether or not a single person was counting the bacteria.

Does Temperature Affect the Rate of Bacterial Reproduction? No, I am not satisfied with the data because the researcher did not explain how he eliminated the possible variables listed in question #3. Also, there is no mention of a control group.

Does Temperature Affect the Rate of Bacterial Reproduction? Suppose that we want to test the hypothesis that this type of bacteria reproduces the most at a single temperature. We would need to have several experimental groups and one control group for this experiment. The data from the experiment in the book suggests that this bacteria grows well at 30.5 degrees Celsius.

Does Temperature Affect the Rate of Bacterial Reproduction? (continued) So, we would use this temperature for growing our control group cultures. For our control group, we would put three Petri plates with the bacteria at 30.5  C. Then, we would grow our experimental groups (three Petri plates in each group) at perhaps three different temperatures near to 30.5  C, like 26  C, 28  C, and 32  C.

Does Temperature Affect the Rate of Bacterial Reproduction? (continued) In order to have a controlled experiment (that is, one with only one variable) we would need to make sure that all groups have the same nutrient medium, same moisture content, same light level, same type of bacteria, same type of Petri plates, same person counting the bacteria, etc.

Control 30.5  C Exp 1 26  C Exp 2 28  C Exp 3 32  C

Prefixes in the SI PrefixSymbolMultiplierExp yotta-Y zetta-Z exa-E peta-P tera-T giga-G mega-M kilo-k hecto-h deca-da

Prefixes in the SI PrefixSymbolMultiplierExp deci-d centi-c mili-m microµ nano-n pico-p femtof atto-a zepto-z yocto-y

Table 5. SI prefixes FactorName Symbol yottaY zettaZ exaE petaP teraT 10 9 gigaG 10 6 megaM 10 3 kilok 10 2 hectoh 10 1 dekada FactorName Symbol decid centic millim microµ nanon picop femtof attoa zeptoz yoctoy Metric System Prefixes

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kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

kilometermetercentimetermilimeter

The Scientific Method Hypothesis: a testable answer to a scientific question –Example: My female students are more daring than my male students

The Scientific Method Infer: to make a guess that is based on observations –Example: I infer that ___________ didn’t get enough sleep because they are sleeping in class.

The Scientific Method Variable: anything that can change during an experiment –Temperature –Light –Age

The Scientific Method A controlled experiment: one in which only one variable changes at a time

The Scientific Method Control group: a group that serves as a reference for other groups Experimental group: a group in which scientists deliberately change one variable.

The Scientific Method Theory: an explanation of things or events based upon many observations and experiments. –A working model which may or may not be true –Cell Theory: all living things are made of cells. –Evolutionary Theory –The “Big Bang” Theory

The Scientific Method Law: a statement of how things work in nature that seems to be true all the time. –A “fact of life” –First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed.