Scientific Method and Metric System

Metric Measurements

• Remember the American Choppers’ confusion with English measurements?!?

• Always measure mass in grams, distance in meters, volume in liters, temperature in ºC, and time in seconds

• Remember how to convert from one unit to another using the metric staircase (count stairs and remember the direction to move decimal point)

Observation Skills

• Observation skills in the Clue-style clip & Basketball clip.

• QUALITative observations: based on the QUALITIES of an object using 5 senses

• QUANTITative observations: when you count or measure QUANTITIES of an object

• Inferences: logical statements that attempt to explain the pattern of observations using prior knowledge.

Precision vs. Accuracy

• Precision: exactness of a measurement• Accuracy: a description of how close a

measurement is to the true value of the quantity measured

• Ex: If you measure the long jump with a tape measure that has a broken tip (top), you can still read 4.14m PRECISELY. But that number is not ACCURATE because it’s not the actual distance of the jump.

Steps of the Scientific Method

Parts of the Scientific Method

• Scientific Method: a logical, scientific approach to problem solving

• Testable question: question that asks how changing one variable will affect results

• Purpose: written as “To observe…” or “To measure…”

• Hypothesis: a 3 part sentence that describes the experiment, makes a prediction and presents an educated guess to explain predicted results

• How does increasing the hole in a parachute affect drop time?

• To observe how increasing the diameter of the hole affects parachute drop time.

Scientific Method 2

• Independent variable: the factor “I” change in an experiment

• Dependent variable: Data collected when experimenting

• Standardizing variables: parts of exper. NOT influenced by the IV; Stuff that Stays the Same

• Control group: the group that receives no treatment or a standard treatment…gives baseline reading for comparing results

I: parachute hole diameter

D: drop timeSV: drop height, parachute mass, length of strings, etc

CG: unaltered parachute with standard hole size (compare data to this!)

Writing a Hypothesis

• If the independent variable is increased/decreased (choose one!)…

• Then the dependent variable will increase/decrease (predict only one!)…

• Because of “this scientific principle” (you will need to do some research for this!)

• Ex: If the size of the hole in a parachute is increased then its drop time will decrease because air resistance will decrease allowing the parachute to fall faster.

Data

• Recorded in a data table– At least 3 columns of test groups w/units– 10 trials listed w/average row!

• Analyzed using graphs:– Pie chart: comparing percentages– Bar graph: comparing values– Line graphs: showing trends between the independent

variable and the dependent variable• Plot only averages!• X axis has the indep. variable• Y axis has the dep. variable

Trial

Ind var 1

Ind var 2

Ind var 3

1

2

3

4

5…

..10

Avg

Parts of a Conclusion

• Rewrite your hypothesis word for word!• Describe to the reader the trend shown in the

graph. Use qualit.(observ.) and quantit. (#) data!

• Explain the science that rationalizes the trend you saw.• Provide 2 sources of error that may have thrown off your data

Use formal writing: No I, me, my or you!

• I think the reason for the results….

• You need to gather your materials….

• My results show…

• One possible reason for the results…

• Gather the following materials…

• The results show…

Steps of the Scientific Method