Scientific Method
What is WATCO?
What are the consequences of?
Identify IV and DV on the following question: What are the consequences of soap on the growth of bacteria?
IV: amount of soap
DV: growth of bacteria
Steps for performing the experiment
Procedure
What are the 3 steps to swab a petri dish with bacteria?
1. get q-tip wet
2. swab surface
3. swab petri dish
If I add different amounts of juice to plates of bacteria, the bacteria with the most amount of juice will grow the most. What is the variable being tested?
amount of juice
Independent and dependent variable
What would be the hypothesis for the following question: What are the consequences of soap on the growth of bacteria?
If soap is added to the petri dish, then less bacteria will grow.
Name one of the 3 things that are important to remember when writing a procedure
1. Clear and specific enough that someone can repeat it.
2. Only one variable can change.
3. Must include a way to quantify your Independent and dependent variables.
What are the 3 ways to measure the DV?
1. Count
2. Measure
3. Test for the presence
Homer notices that his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of "treatment" there is no change in the appearance of the green slime on either side of the shower.
WHAT IS THE CONTROL GROUP?
The half of the shower that was not sprayed with coconut juice.
How do you form a WATCO question?
What are the consequences of Independent Variable on Dependent Variable?
The variable that depends on the one being tested is called:
Dependent Variable
What are the materials needed for the following experiments? Give at least 4.
Carlos swabs 3 petri dishes with bacteria from the same location. He stores all of them at room temperature. He adds 6 drops of vinegar to one dish, 3 drops to another dish, and no vinegar to the last dish. He measures the growth of the bacteria over 1 week.
3 petri dishes
3 q-tips
Water for swabbing
Vinegar
Pipette
How would you measure the DV? If I spend more hours practicing basketball, then I will be able to score more points in a game
1. Tables
2. graphs
3. Charts and diagrams
What is a hypothesis statement?
an educated guess or prediction
Variable
What is the WATCO question to the following experiment?
What are the consequences of temperature on the growth of bacteria?
The group you leave alone in an experiment
Control group
You think you’ve found a cure for the common cold. You test it out by finding 100 sick students and dividing them into 2 groups of 50 students each. You give Group A the new drug you just made. You give Group B regular medicine. You monitor both groups for 1 week. You observe that, on average, students in Group A are sick for 6 days, and students in Group B are sick for 3 days.
WHAT IS THE CONTROL GROUP?
What does it mean to hold all variables constant?
None of the variables should change except the independent and dependent!
Carlos swabs 3 petri dishes with bacteria from the same location. He stores all of them at room temperature. He adds 5 drops of milk to one dish, 3 drops to another dish, and no milk to the last dish. He measures the growth of the bacteria over 1 week. WHAT IS THE VARIABLE BEING TESTED?
Amount of milk
What is wrong with this experiment?
Michael swabbed 3 petri dishes with bacteria. He added 10 drops of soap to one, 5 drops of soap to another, and 0 drops of soap to the last one. He stored one plate in the fridge, one plate in the incubator, and one plate at room temperature. He measured the growth of the bacteria for the next 3 days.
More than one variable is changing.
One way you can improve an experiment?
–Repeating them (to see if we get the same results)
–Using a larger sample size
–Eliminating sources of error
–Changing only ONE variable and making sure all others are controlled
–Finding better ways to measure the IV and DV
Carlos planted three identical bean sprout plants in soil. He gave one plant soil with a pH of 4, he gave another soil with a pH of 5, and he gave the other soil with a pH of 6. He stored all 3 plants next the window, where they 100 watts of sunlight every day. He gave them all 10 mL of water every day. He measured how much they grew over 1 month.
What is the DV and IV?
Dependent Variable: growth of plant
IV: pH