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 BiologyScientific 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 Investigations2. Comparative Investigations3. 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

Tomato Plant Growth

Experiment Graph

Date Plant A Height Plant B Height

Data Table

What goes on the XAxis? Day

What goes on the YAxis? Temperature

Temperatures In NY City

Day Temperature

1 43° F

2 53° F

3 50° F

4 57° F

5 59° F

6 67° FOn your notes draw a line to the

correct graph

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 Graphs1. Label axes – be specific, use units

a. time – hour, minutesb. 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!