Metric and Method Science Notes

​It's Science...An intro.

By Christopher Powers

Metric System

US vs. The World

• For everyday measuring in the United

States, we use the British system of
pounds, gallons, and feet, but science
(and the rest of the world) uses the easier
metric system.

Base Units

All measurements in the metric system are
based upon the basic units of meters, liters,
and grams.
•Meters measure LENGTH

•Liters measure VOLUME

•Grams measure MASS

• Length - distance between two

points
–SI unit → meter (m)

• Volume – the amount of space

occupied by an object
– SI unit – Liter (L)

Mass - the amount of matter

SI unit → gram (g)

Length - distance between two
points

SI unit → meter (m)

Prefixes

The case of the metric system comes in
its use of prefixes. The British system
uses completely different units when
changing between small and large
measurements. The metric system
simply uses prefixes.

millimeter

Prefix

Ladder Method

K = Kilo

h=hecto

da=deca

base = meters (m) liters (L) grams (g)

d= deci

c = centi

m=milli

Practice Conversions

G M k h dk d c m µ

Base

• Convert 34 m to cm ________

• Convert 2000 g to kg _______

Put these numbers in scientific notation.

1) 1000
2) 0.01
3) 12
4) 0.987
5) 596
6) 0.000 000 70
7) 1,000,000
8) 0.001257
9) 987,653,000,000
10) 8

PROBLEMS

1)_____

2) _____

3) _____

4) _____

5) _____

6) _____

7) _____

8) _____

9) _____

10) _____

ANSWERS

PRACTICE PROBLEMS

Convert from Scientific Notation to whole numbers

or decimals

PROBLEMS

ANSWERS

1) 4.9 X 102

2) 3.75 X 10-2

3) 5.95 X 10-4

4) 9.46 X 103

5) 3.87 X 101

6) 7.10 X 100

7) 8.2 X 10-5

1)

___

2)

____

3)

____

4)

___

5)

_____

6)

_____

7)

_____

Introduction to Significant

Figures

&

Scientific Notation

Significant Figures

• Scientist use significant figures to

determine how precise a measurement
is

• Significant digits in a measurement

include all of the known digits plus one
estimated digit

For example…

• Look at the ruler below

• Each line is .1 cm
• You can read that the arrow is on 13.3 cm
• However, using significant figures, you must

estimate the next digit

• That would give you 13.30 cm

Let’s try this one

• Look at the ruler below

• What can you read before you

estimate?

• 13.8 cm
• Now estimate the next digit…
• 13.85 cm

The same rules apply with all

instruments

• The same rules apply
• Read to the last digit that you know
• estimared the final digit

Let’s try graduated cylinders

• Look at the graduated cylinder below

• What can you read with confidence?
• __ ml
• Now estimate the last digit
• __ ml

One more graduated cylinder

• Look at the cylinder below…

• What is the measurement?
• ____ ml

Rules for Significant figures

Rule #1

• All non zero digits are ALWAYS

significant

• How many significant digits are in the

following numbers?

1. 274

a.

2. 25.632

1.

3. 8.987

1. __ Significant Figures

2. __ Significant Digits

3. __ Significant Figures

Rule #2

• All zeros between significant digits are

ALWAYS significant

• How many significant digits are in the

following numbers?

1. 504

1. 60002

1. 9.077

1. __ Significant Figures

1. __ Significant Digits

1. __ Significant Figures

Rule #3

• All FINAL zeros to the right of the

decimal ARE significant

• How many significant digits are in the

following numbers?

1. 32.0

1. 19.000

1. 105.0020

1. __ Significant Figures

1. __ Significant Digits

1. __ Significant Figures

For example

0.0002
6.02 x 1023

100.000
150000
800

Significant Digit

Significant Digits

6 Significant Digits
2 Significant Digits
1 Significant Digit

How many significant digits are in the following numbers?

Rule #5

• All counting numbers and constants

have an infinite number of significant
digits

• For example:

1 hour = 60 minutes
12 inches = 1 foot
24 hours = 1 day

How many significant digits

are in the following numbers?

0.0073
100.020
2500
7.90 x 10-3

670.0
0.00001
18.84

2 Significant Digits
6 Significant Digits
2 Significant Digits
3 Significant Digits
4 Significant Digits
1 Significant Digit
4 Significant Digits

Rounding

200.99
18.22

Round to 300
Round to 18

Scientific Method Notes

Unit 1: Intro to Biology

What are the steps

to the Scientific

Method?

There are 7 Steps You Need to Know

1.

Make Observations and Ask Questions

2.

Do Background Research

3.

Form a Hypothesis

4.

Test an Experiment

5.

Organize Data/Results

6.

Analyze Results and Draw Conclusions
a.

Is the hypothesis true, partially true, or false?

7.

Report Results
a.

If hypothesis is false, think and try again! Form a new
hypothesis

The Scientific Method

● These steps do not

always follow this order!

● Sometimes scientists

have to go back and
forth between the steps
when working on an
experiment.

Scientific Thinking and Process

●

Purpose = to determine the relationship between the
independent and dependent variables

●

Scientific inquiry starts with careful and systematic observations

●

These observations lead to scientific questions

●

Ex: My roommate has a saltwater fish tank. One day when she was
cleaning out the tank, she spilled water everywhere including on
the plants near the tank. The next day I noticed the plants did not
look well.
○

QUESTION: Does salt water negatively affect plant growth?

Forming a Hypothesis

●Hypothesis = predicts the relationship between the independent and
dependent variables; must be testable
○Even if it is supported by an experiment, it will continue to be tentative

○Formatting: If (independent variable), then (dependent variable)
because (reason).

●Independent Variable = condition that is manipulated by the scientist;
“what I the Scientist am changing;” the effects of this change can be
measured in the experiment; the cause

●Dependent Variable = observed and measured during an experiment;
changes upon the manipulation of the independent variable; the effect

●What are the independent and dependent variable from our example?

Multiple Choice

Something that you keep the same in an experiment is called a(n) _________________________.

• variable

• control

• procedure

• conclusion

Multiple Choice

I want to know if low strength bleach, medium strength bleach, or maximum strength bleach will get Heinz ketchup stains out of white T-shirts the best. What is the variable in this experiment?

• the type of stain

• the strength of the bleach

• the color of shirt

• the brand of ketchup

Multiple Choice

What is a dependent variable?

• What a scientist changes in an experiment to test their hypothesis

• What scientist measure to see if it responded to a change

• What happens when you do an experiment

• What you keep the same throughout all experimental groups

Let’s practice!

●If a student holds their breath longer, then the amount of carbon
dioxide they exhale will increase. What are the IV and DV?

●If three plants are each placed under different lights (red, green,
and blue), then the plant under the green light will grow the most
and the plant under the blue light will grow the least. What are the
IV and DV?

Multiple Choice

A statement that can be tested by conducting an experiment.

• Constant ______

• Conclusion ______

• Hypothesis ______

• Independent Variable ______

• Dependent Variable ______

Multiple Choice

The _________________________ answers the problem you are trying to solve in an experiment and explains the results to others.

• procedure

• hypothesis

• conclusion

• data

Conducting an Experiment

●

Investigate the relationship between the independent and
dependent variables

●

Constants (Controlled variables) = conditions that do not
change in an experiment

●

Control Setup = a setup that does not contain the independent
variable; used to compare the results of the experiment

●

Trials = experiments are repeated multiple times

●

Always use proper lab safety!!!!

●

What would be the constants and the control set up for our
example?

Collecting and Reporting Data

● Scientists collect two types of data:

○ Quantitative = numeric measurements

■ objective → should be the same no matter who

measures

○ Qualitative = description in words

■ subjective → based on observations that could

vary from person to person

● What kind of data did we collect in the example?

Multiple Choice

The information you collect while doing your experiment is called

• conclusions

• data

• hypotheses

• procedures

Multiple Choice

A(n) ___________________________ is what you can learn about an object by using your 5 senses.

• Qualitative Observation

• Quantitative Observation

• Inference

• Hypothesis

Multiple Choice

The trees outside of the school have large, green leaves growing on them. Is this a Qualitative Observation, Quantitative Observation, or an Inference

• Qualitative Observation

• Quantitative Observation

• Inference

Let’s practice!

Collecting and Reporting Data

● Often collect the data into a data table during the

experiment

● Report data in charts, graphs, tables, or models to

demonstrate the relationship being investigated
between the variables

● For most of the labs we will do in Biology, we will use

graphs or models to represent our results

● After collecting data, I notice growth and no growth.

Graph Types

●

In Biology, you will most likely use
either a bar graph or a line graph

●

Bar graph = used for
comparisons between groups

●

Line graph = used to show
change over time

●

For our example, what kind of
graph should I use to represent
my data?

What do you notice about this graph?

What do you notice about this graph?

A good graph includes…

● A descriptive title

○ Ex: The effect of IV

on DV

● Labeled x and y axes

○ Always include units!

● Appropriate spacing

and scale

● Color coded or key

present

● On graph paper or

typed (formal report)

● Remember DRY MIX

○ DRY = Dependent

Variable, Response,
Y-axis

○ MIX = Manipulated,

Independent
Variable, X-axis

Let’s check this graph!
●

A descriptive title

●

Labeled x and y axes
(units)

●

Appropriate spacing and
scale

●

Color coded or key present

●

On graph paper/typed

●

Variables in the right place
○

Dependent = y axis

○

Independent = x axis

Let’s practice graphing!

●Plant A was given tap water

●Plant B was given salt water

Day

Height for Plant A

Height for Plant B

0

3 cm

5 cm

1

4 cm

5 cm

2

6 cm

5.5 cm

3

7 cm

5.5 cm

4

10 cm

5.5 cm

Multiple Choice

Variable that you manipulate during an experiment

• Constant ______

• Conclusion ______

• Hypothesis ______

• Independent Variable ______

• Dependent Variable ______

Multiple Choice

The variable that does not change during an experiment

• Constant ______

• Conclusion ______

• Hypothesis ______

• Independent Variable ______

• Dependent Variable ______

Multiple Choice

States whether or not the hypothesis was supported

• Constant ______

• Conclusion ______

• Hypothesis ______

• Independent Variable ______

• Dependent Variable ______

Analyze Data and Draw Conclusions

●

Your conclusion should answer the following questions
○

Was your hypothesis supported? Explain using data
evidence!

○

What could you do differently next time?

○

How could you explore this topic further?

●

You should communicate your findings to others
○

In Biology, you will communicate them to me in your lab
write ups/reports

○

Professional scientists publish in peer-reviewed journals

●

What could we conclude about our example experiment?