WARM UP!
•Write down ONE
safety rule
•What is a hypothesis?
Today’s Objectives:
We will:
1. compare the different types of
investigations we will be doing
2. review the scientific method/variables
3. discussing accuracy vs. precision
Introduction
to Biology
Scientific method
Graphing
BIOLOGY = The study of life
• Etymology – using parts of words (prefixes and
suffixes) to figure out what the word means.
• BIO = Life
• OLOGY = the study of
There are different ways to solve
problems.
• Scientists use 3 different types of
investigations to solve problems.
1. Descriptive Investigations
2. Comparative Investigations
3. Experimental Investigations
Descriptive Investigation
• With a partner, in the box provided describe
what you think descriptive sounds like or
means.
• Used to observe and describe
• Draw a line to the Descriptive investigation.
Comparative Investigation
• In the box provided, write what you think
comparative sounds like or means.
• Used to collect data and make a comparison.
• Draw a line to the Comparative investigation.
Experimental Investigation
• What does experimental sound like or mean?
• Used to manipulate or change variables to
gather evidence to support or refute a
relationship or hypothesis.
• Draw a line to the experimental investigation.
• These are the types of investigations where
scientists use the scientific method.
Scientific Method (6 steps)
• Define the PROBLEM – usually a question.
– Which type of fertilizer causes the most growth in
tomato plants?
• Do RESEARCH – provides background
information.
– The scientist researched other experiments to see
the effects of fertilizer on tomato plants.
• Create a HYPOTHESIS – Make a prediction.
MUST me testable and measureable.
– If 1 oz. of Miracle-Gro fertilizer is applied to the
tomato plants every other day for 14 days, the
plants will show the most growth when compared
to plants given other fertilizers.
Which hypothesis is better?
• If I study for my biology test, I will get a good
grade.
• If I study biology every night for 30 minutes, I
will earn an A on my biology test.
Which hypothesis is better?
• If I water my yard for 30 minutes a day, 5 days
a week, my yard will grow.
• If I water my yard, the grass will grow.
Which hypothesis is better?
• Sugar kills worms.
• If I add 5 mL of sugar water to the worm, it
will kill it.
• Perform an EXPERIMENT – this tests your
hypothesis
– He tests the fertilizers called Scott’s Liquid Grow,
Miracle-Gro, and Fertilome Super Grow. He also
tests one group of plants that do not receive any
fertilizer. All plants are given the same amount of
water, sunlight and potting soil. The scientist
measures the height of the plants every 2 days for
14 days.
• GATHER and ANALYZE DATA – use data from
your experiment
• USE DATA TABLES!
• Form a CONCLUSION – based on the data
from the experiment.
– Based on the data provided, it has been shown
that applying Miracle Gro increased the growth of
the plant more than the other fertilizers.
• Controlled Experiment – only 1 variable is
being tested at a time
1. Variable – factor in an experiment that can
change
– Ex: temperature, time, size, amount or kind of
material
2. Variable that is deliberately changed –
manipulated or independent variable
• Typically the manipulated or independent
variable can also be considered as the
experimental.
Manipulated = Independent = Experimental
3. Variable that changes in response to or
because of the manipulated variable –
responding or dependent variable
Responding = Dependent
4. Experimental group – contains the variable
being tested
– Ex. The tomato plants with the fertilizer
5. Control group – does not contain the
experimental variable
– Ex. The tomato plants without fertilizer
• FACTORS THAT SCIENTISTS PURPOSELY
CHANGE:
MIX – Manipulating variable, Independent variable, X axis
• FACTORS THAT MAY CHANGE BECAUSE OF THE
MANIPULATED VARIABLE
DRY – Dependent variable, Responding variable, Y axis
What could the experimental variable be?
The amount of light exposure
• Example:
• A scientist designs an experiment to see which
kind of fertilizer causes the most growth in
tomato plants. He tests Scott’s Liquid Grow,
Miracle-Gro, and Fertilome Super Grow. He also
tests one group of plants that do not receive any
fertilizer. All plants are given the same amount of
water, sunlight and potting soil. The scientist
measures the height of the plants every 2 days for
14 days.
Experimental variable = kind of fertilizer
Control group = group that received no fertilizer
Manipulated (independent) variable = kinds of fertilizer
Responding (dependent) variable = plant height
• When gathering and analyzing data from an
experiment:
– Data should be gathered from large sample sizes
in order to show better results.
Ex: use many tomato plants (100+) when testing
for fertilizers
– ACCURACY - The closeness of a measurement to
the true value of what is being measured
Ex: Hitting close to or on the bulls eye of a
target
– PRECISION/PRECISE - exact or repeated
measurements very close in value
Ex: Hitting close to or on the bulls eye of a
target multiple times
• Form a conclusion based on the data from the
experiment
– If data supports hypothesis – repeat the
experiment for verification
– A hypothesis tested and confirmed often enough
that it is unlikely to be disproved and becomes a
theory
– If data does not support hypothesis – refine or
change the experiment, then repeat experiment
Once an experiment is completed, the
data is put in to a data table and a
graph can be created.
EXPERIMENT
DATA TABLE
GRAPH
Organizing Lab Data
Experiment
Graph
Tomato Plant Growth
Date
Plant A Height
Plant B Height
Data Table
What goes on the X
Axis? Day
What goes on the Y
Axis? Temperature
On your notes draw a line to the
correct graph
Temperatures In NY City
Day
Temperature
1
43° F
2
53° F
3
50° F
4
57° F
5
59° F
6
67° F
Organizing Lab data
• Line Graph
• Bar Graph
• Pie Graph
Variables on the graph
D = Dependent variable
or
R = Responding variable
on
Y = Y axis
M
I
X
Manipulated variable or Independent variable on the X axis
Good Graphs
1. Label axes – be specific, use units
a. time – hour, minutes
b. weight – pounds, grams
2. Numbers on axes must be in even increments
and evenly spaced
a. 2, 4, 6, 8, 10
b. 5, 10, 15, 20
c. 1, 5, 7, 10, 12
WRONG!
FYI
SAFETY Quiz
TOMORROW!