Good morning!
Observations vs. Inferences
Observation
• an act of recognizing and noting a fact or occurrence often involving
measurement with instruments
What does it
mean to observe?
Observations
What is an
observation you
can make from this
picture?
Observations
• What is an observation you can make from this picture?
Observations
•What is an observation you can
make from
this picture?
Inference
• to derive as a
conclusion from facts or premises
What does it mean
to infer?
Making Inferences
• You observe that the sky at noon is
darkening.
What would the inference be?
Making Inferences
• The principal interrupt s class and calls a
student from the room.
What would the inference be?
Making Inferences
• All high school students are bringing lunch from home.
What would the inference be?
Science Variables
Cause and Effect
Relationships
Variables
• Manipulated Variable—Independent Variable
Factor or condition that is intentionally changed by the scientist in an experiment!
In an experiment, you may have only one manipulated variable.
Variables
• Responding or dependent variable
changes in response to the change the scientist makes to the independent variable
The new value of the dependent variable is caused by and depends on the value of the independent
variable!
Example:
• if you open a faucet (the independent variable), the quantity of water flowing (dependent variable) changes in
response--the water flow increases.
Opening the faucet is intentionally changed!
The amount of water flowing will change!
Variables
• Controlled Variables
Controlled variables are quantities that a scientist wants to remain constant, and he must observe them as carefully as the
dependent variables.
There may be many controlled variables in an experiment!
Practicing Variables…..
• What variables could effect the number of
fans at the football game on Friday?
Practicing Variables…..
• What variables could effect the number of books sold by a door to door sales person?
Question
• Two groups of students were tested to compare their speed working math
problems. Each group was given the same problems. One group used
calculators and the other group was not
allowed calculators.
What is the Independent Variable?
• Two groups of students were tested to compare their speed working math problems. Each group was given the same problems. One group used calculators and the other group was not allowed calculators.
What was manipulated/changed?
One group used calculators and one did not!
Dependent/Responding Variables
• What was supposed to change in the experiment?
The speed at working math problems.
Controlled Variables
What stayed the same?
Worked the same math problems!
Quadratic Equation
Enter the coefficients for the Ax2 + Bx + C = 0 equation and Quadratic Equation will output the solutions (if they are not imaginary).
Question
• A student wanted to test how the mass of a paper airplane affected the distance it would fly. Paper clips were added before each test flight. As each paper clip was
added, the plane was tested to determine
how far it would fly.
What is the Independent Variable?
• A student wanted to test how the mass of a paper
airplane affected the distance it would fly. Paper clips were added before each test flight. As each paper clip was added, the plane was tested to determine how far it would fly.
Independent variable (manipulated)---what was changed?
Mass of airplane—number of paper clips added
Dependent/Responding Variables
• What was supposed to change in the experiment?
The Distance flown by the airplane was the dependent variable.
Controlled Variables
• What types of things would have to stay the same?
1. Type of paper
2. Where it is being flown?
3. Use the same plane!
4. Same person throwing it with the same strength!
Question
• Does fertilizer make a plant grow bigger?
What is the Independent Variable?
• Does fertilizer make a plant grow bigger?
Amount of fertilizer
measured in
grams
Dependent/Responding Variables
• What was supposed to change in the experiment?
Growth of the plant measured by its height
or
Growth of the plant measured by the number of leaves
Controlled Variables
• Same plants
• Same soil
• Same size pot
• Same amount of water and light
• Make measurements of growth at the
same time
Tree Growth
The independent variable here is the YEAR and it is plotted on the horizontal axis.
The independent variable is
always located on the horizontal axis. What is the independent variable?
The dependent variable is the AVERAGE HEIGHT and this is plotted on the vertical axis. The height is a dependant variable because we are trying to determine a
relationship between the year and the height. In particular, we are trying to see how the height depends upon what year it is.
Hypothesizing
Hypothesizing
• Predicting is the process of using
observations or data along with other kinds of scientific
knowledge to forecast future events or
relationships.
Hypothesizing
• Manipulated
• Responding
• Controlled
• A hypothesis is a special kind of prediction that
forecasts how one variable will affect a second variable.
• What kind of evidence indicates that high
school students prefer one kind of pizza more than another?
• If high school students are
questioned about pizza, then they will prefer pepperoni over cheese pizza.
Use an If____________, then __format.
Hypothesizing
• Use an If____________, then __format.
• If the temperature of sea water increases,
then the amount of salt that will dissolve in
that water increases.
Steps for Writing a Good Hypothesis
• Identify variable in a given event or relationship.
• Identify the pair of variable that might be logically related.
• Identify the manipulated and responding variable.
• If the (manipulated variable) increases or
decreases, then the (responding variable)
will increase or decrease.
• Manipulated variable: depth of Reed’s Lake
• Responding: water temperature
Hypothesis:
• Manipulated variable: baseball batting practice
• Responding: batting average
Hypothesis:
Your task…….
• Think of an experiment using paper---an airplane or whirly bird---that can be done in class.
• Materials----different types of paper, straws, tape, paper clips, fan, tape measure and stop watch (let me know if you think of something else)
• List the problem, materials, hypothesis
(if………then….), manipulated, independent and controlled variables.
Fold----DO NOT CUT OFF!
• Title:
• Problem:
• Hypothesis:
• Manipulated Variable:
• Responding Variable:
• Controlled Variables (list 4):
• Materials:
• Data Table:
• Graph:
• Conclusion:
• Error Analysis
See me for the
newsprint to write
your report on!
Homework
• Read Section 1-3
– Pages 16-21
– Answer questions #1 – 4 and 6
