THE SCIENTIFIC METHOD

 Scientific Method – a series of logical steps to follow in order to solve problems in science.

Spider Plants Ask a Question: How much plant food will produce the most growth?

 Scientific Method – a series of logical steps to follow in order to solve problems in science.

Spider Plants Construct a Hypothesis: If/Then If 3 grams of plant food are added, then the plant will grow 10 cm more.

 Scientific Method – a series of logical steps to follow in order to solve problems in science.

Spider Plants Perform an Experiment: - Independent variable - Control

Spider Plants YOUR TURN…….. Design an experiment

What are some variables? anything that can change in an experiment; anything that can be manipulated.  What are some variables?

What are some variables? A student wishes to study the effect of plant food on the growth of spider plants. She designs an experiment with three setups. Each setup contains five healthy spider plants grown in potting soil. All plants receive the same amount of sunlight and water. 1 gram of plant food is added to each plant in setup one. 3 grams of plant food is added to each plant in setup two. The third setup receives no plant food. After one month, she measures the height of the plants. What are some variables? (anything that can be manipulated)

anything that can change in an experiment; Variable – anything that can change in an experiment; anything that can be manipulated. There are two types of variables: Independent variable: 2. Dependent variable:

Variables – Independent variable: variable that is changed in the experiment. -- What is being investigated (tested)

Independent variable? Amount of plant food A student wishes to study the effect of plant food on the growth of spider plants. She designs an experiment with three setups. Each setup contains five healthy spider plants grown in potting soil. All plants receive the same amount of sunlight and water. 1 gram of plant food is added to each plant in setup one. 3 grams of plant food is added to each plant in setup two. The third setup receives no plant food. After one month, she measures the height of the plants. Independent variable? Amount of plant food (what is being investigated/tested)

2. Dependent variable: the variable being measured in an experiment.

Dependent variable? Height of the plants A student wishes to study the effect of plant food on the growth of spider plants. She designs an experiment with three setups. Each setup contains five healthy spider plants grown in potting soil. All plants receive the same amount of sunlight and water. 1 gram of plant food is added to each plant in setup one. 3 grams of plant food is added to each plant in setup two. The third setup receives no plant food. After one month, she measures the height of the plants. Dependent variable? Height of the plants (the variable being measured )

What would happen if we gave the plants in setup two more water? Good experiments are designed to investigate only one variable at a time Constants: those variables that are kept the same

A student wishes to study the effect of plant food on the growth of spider plants. She designs an experiment with three setups. Each setup contains five healthy spider plants grown in potting soil. All plants receive the same amount of sunlight and water. 1 gram of plant food is added to each plant in setup one. 3 grams of plant food is added to each plant in setup two. The third setup receives no plant food. After one month, she measures the height of the plants. (those variables that are kept the same) Constants? Spider plants, potting soil, type of plant food, sunlight, and water

How do we know if the plant food made the plants grow more?   Control: item or group that does not receive experimental treatment Used for comparison

Control? The plants in Group 3 A student wishes to study the effect of plant food on the growth of spider plants. She designs an experiment with three setups. Each setup contains five healthy spider plants grown in potting soil. All plants receive the same amount of sunlight and water. 1 gram of plant food is added to each plant in setup one. 3 grams of plant food is added to each plant in setup two. The third setup receives no plant food. After one month, she measures the height of the plants. Control? The plants in Group 3 (item that does not receive treatment)

What are some variables? Two groups of 50 rats are tested in a lab. Both groups are kept in a 5 x 5 x 2 ft cage in a temperature controlled room (25° C). Both groups are provided with water and fed 125 grams of food daily. Group 1 is given a growth hormone. Group 2 does not receive any growth hormone. At the end of six months, the rats are weighted. What are some variables?

Independent variable? Growth hormone Investigating? Two groups of 50 rats are tested in a lab. Both groups are kept in a 5 x 5 x 2 ft cage in a temperature controlled room (25° C). Both groups are provided with water and fed 125 grams of food daily. Group 1 is given a growth hormone. Group 2 does not receive any growth hormone. At the end of six months, the rats are weighted. Independent variable? Growth hormone Investigating?

Dependent variable? Weight of the rats Measure Two groups of 50 rats are tested in a lab. Both groups are kept in a 5 x 5 x 2 ft cage in a temperature controlled room (25° C). Both groups are provided with water and fed 125 grams of food daily. Group 1 is given a growth hormone. Group 2 does not receive any growth hormone. At the end of six months, the rats are weighted. Dependent variable? Weight of the rats Measure

Cage, temp, water, and food Two groups of 50 rats are tested in a lab. Both groups are kept in a 5 x 5 x 2 ft cage in a temperature controlled room (25° C). Both groups are provided with water and fed 125 grams of food daily. Group 1 is given a growth hormone. Group 2 does not receive any growth hormone. At the end of six months, the rats are weighted. Constants? Cage, temp, water, and food

Rats not receiving growth hormone Two groups of 50 rats are tested in a lab. Both groups are kept in a 5 x 5 x 2 ft cage in a temperature controlled room (25° C). Both groups are provided with water and fed 125 grams of food daily. Group 1 is given a growth hormone. Group 2 does not receive any growth hormone. At the end of six months, the rats are weighted. Control? Rats not receiving growth hormone

The Parts of an Experiment:   Variable – anything that can change in an experiment Types of variables: 1. independent variable: variable that is changed or manipulated in the experiment. 2. dependent variable: variable that responds to/depends on the conditions of experiment; the variable being measured. Constants: those variables that are kept the same (so that there are no additional variables) Control: item or group that does not receive experimental treatment(independent variable)

 The steps in the Scientific Method: Observation/Question Hypothesis Experiment Collecting/Analyzing data Draw Conclusion Communicate Results

Observation/Form of a question Hypothesis – a proposed explanation for an observation Experiment – good experiments are designed to investigate only one variable at a time and must include a control. Collecting/Analyzing data: collect all data and organize into tables, charts, or graphs so that it can be clearly explained. Draw Conclusion – determine if hypothesis is proved to be true or false. Communicate Results: Most scientists publish their results; including the details of their experiment, all the data that was collected, and their conclusion and prediction.