the scientific method. scientific method – a series of logical steps to follow in order to solve...

THE SCIENTIFIC METHOD

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

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.

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 conditions that are kept the same (so that there are no additional variables)   Control: item or group that does not receive experimental treatment(independent variable)

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.

Variable – anything that can change in an experiment; anything that can be manipulated.

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.

(anything that can be manipulated)

Variable – anything that can change in an experiment; anything that can be manipulated.

Types of variables:

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

1. Independent variable: variable that is changed in the experiment. The treatment; what is being tested

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(The treatment; what is being tested)

Variable – anything that can change in an experiment; anything that can be manipulated.

Types of variables:

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

1. Independent variable: variable that is changed in the experiment. The treatment; what is being tested

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?

Constants:        those variables that are kept the same

Good experiments are designed to investigate only one variable at a time

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.

Constants? Spider plants, potting soil, type of plant food, sunlight, and water

(those variables that are kept the same)

 Control: item or group that does not receive experimental treatment Used for comparison

How do we know if the plant food made the plants grow more?

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)

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?

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

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

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

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

You know soda promotes tooth decay, but you want to know if all sodas have the same effect. You get 5 models of teeth (same chemical composition of teeth) and place them different sodas after weighing them. You get a 6th model and place it in water. You keep all of the models in the same room at room temperature. After 2 months, you measure the mass of the models. Constants?Control?Independent var?Dependent var?

You own 5 goldfish. You feed them daily early in the morning, but you notice that they are not growing. You want to know if the time of day you feed the fish affects the growth of fish. You purchase 5 new goldfish of the same size, put them into 5 separate 1 gal bowls. You pour 2 quarts of water in each bowl. You feed the fish 1 gram of fish food daily. You feed fish one at 6 am, fish two at 9 am, fish three at noon, fish four at 3pm, and fish 5 at 6 pm. After 12 weeks, you measure the weight of the fish. Constants?Control?Independent var?Dependent var?