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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