scientific method, measurement, and graphing. scientific method an organized way of using evidence...

Scientific Method, Measurement, and Graphing

Scientific Method An organized way of

using evidence to learn about the natural world

A. Problem 1. observation- gathering

evidence using the senses (sight and hearing) Inference- a logical

interpretation based on prior knowledge or experience

A. Problem Observation- gathering evidence using

the senses (sight and hearing) Inference- a logical interpretation based

on prior knowledge or experience B. Hypothesis

A proposed scientific explanation to a problem

“if…then” statement

C. Experiment 1. Two parts to every experiment

A. control group- doesn’t receive a variable B. experimental group- receives a variables

2. Variable: the factors in an experiment that change (2 types) A. manipulated variable (independent variable)- the

variable that you can actually change Only one variable can be changed at a time On a graph, the IV is on the x axis

B. Responding variable (dependent variable)- the variable that will change or respond to the IV

3. Constant (controlled variable)- things that remain the same in an experiment

D. Record and Analyze Data Info collected during an experiment 2 main types of data:

1. Quantitative data- expressed as numbers obtained by counting or measuring

2. Qualitative data- descriptive and involves characteristics that can’t be counted

E. Conclusion Summary of experiment, using the data

to determine whether a hypothesis is supported or not

A conclusion must have 3 things Restate problem Briefly summarize results Does results support hypothesis?

Example: Do bacteria grow better at higher temps? Hypothesis: If the temp is higher, then the

bacteria will grow better Independent variable: temp Dependent variable: bacteria growth Constant: same type of bacteria, same type

and amount of agar Control: bacteria at room temp

Theory: a well tested explanation that unifies a broad range of observations. Theories can change.

Law: ideas that have been tested many times and accepted as true. Does NOT change.

II. Measurement Metric system (based on units of 10)

litterKm hecto deca meter dm m cm mm

gram

(Unusually)King Henry Died Drinking Chocolate Milk

Metric conversion examples 1. 100 L = ? mL 2. 2.5 m = ? km 3. 8 mg = ? g 4. 5.5 cm = ? mm 5. 4 kg = ? g

Metric conversion examples 1. 100 L = 100,000 ml 2. 2.5 m = 0.0025 km 3. 8 mg = 0.008 g 4. 5.5 cm = 55 mm 5. 4 kg = 4000 g

Measurement A. Length

1. Instrument = rulers, meter stick 2. Units = km, m, cm, mm

B. Mass- amount of matter in an object, doesn’t change Weight- measure of the pull of gravity,

changes 1. Instrument = triple beam balance 2. Units = kg, g, mg

C. Volume The amount of space an object takes up 1. Volume of a liquid:

A. instrument = graduated cylinder, beaker B. units= l , ml

Meniscus- curve in graduated cylinder 2. Volume of a regular-shaped solid:

Formula: length x width x height Unit = cubic centimeter (cm³)

3. Volume of an irregular-shaped object – water displacement

E. Temp 1. Instrument: thermometer 2. Units: degree Celsius 3. freezing point of water = 0ºC 32ºF Boiling point of water = 100ºC

212ºF Body Temp = 37ºC 98.6ºF

F. Density Mass per unit volume 1. Formula- mass/volume

Unit: g/ml 2. Ex: If the volume of a rock is 2 ml and the

mass is 4 g, what is the density? 4 g/ 2ml = 2 g/ml

III. GraphingA. Circle/Pie Graph- shows parts of a

whole (100%) Ex: Gases in the atmosphere

Nitrogen= 78%Oxygen = 21%Trace gases = 1%

B. Bar Graph Compares data - usually 1 quantitative,

1 qualitative data sets Example: Number of students taking a

foreign language 58 – Spanish 10 - German92 – French 9 – Italian

C. Line Graph Used to show change over time - 2

quantitative data sets

Temp (C) Number of bacterial colonies 10 1220 2530 5540 10050 82

Things to have on a graph: 1. Title 2. X and Y axis labeled

A. IV on X axis B. DV on Y axis

3. numbers on axis evenly distributed 4. Key if necessary