Experimental Design

8th Grade Science

Objective: Design a controlled scientific experiment

S1, C2, PO2

What careers or professions use the Scientific Method?

• scientists

• city water/ sewer/ landfills/etc.

• medical professions

• research and development of products

• ??

The Bad News?Test results are in…The diagnosis?

You have blah-blah disease.

The Good News? There might be a cure but the treatment is still

experimental.

• You have to participate in a clinical study to determine the effectiveness of the treatment.

Problem

• Does Blahcure relieve the symptoms of Blah-

Blah disease?

Hypothesis

•The more Blahcure given/taken, the less

evident the symptoms will be.

Independent Variable

• medication

Dependent Variable• Measure the

symptoms of the disease

• Check to see if patient feels better

Constants• Same disease & level of

sickness• Age of participant• Same health conditions of

diet, exercise, vitamins, etc.• Habits such as smoking or

drinking

• Same exam

Control Group• It represents what

is Normal.• Doesn’t get any

treatment.• Give them a

placebo (fake pill).

Experimental Group• Different

amounts of the medication

Treatment DescriptionControl Group 1 Group 2 Group 3

Placebo ( no med)

10 mg of Blahcure

20 mg of Blahcure

30 mg of Blahcure

2. Problem

• Does the amount of fertilizer given to a plant affect how tall the plant

will grow?

Hypothesis

•The more fertilizer used, the taller the

plant will grow.

Independent Variable

• fertilizer

Dependent Variable• Height of the plant

Constant Variables• Sunlight

• Climate

• Water

• Soil (sandy, peat moss, etc)

Control Group• It represents what

is Normal.• So what is

“normal?”.• Plain dirt…

NORMAL SOIL.

Experimental Group

• Different amounts of fertilizer.

Treatment DescriptionControl Group 1 Group 2 Group 3

No fertilizer 5 grams 10.grams 15 grams

3. Problem• Does the type of tennis shoe

effect the number of shin

splints and knee problems

for runners?

Hypothesis•The __________ (kind

of shoe) will reduce the number of shin

splints/knee problems the runner will have.

Independent Variable• Kinds of shoes

Dependent Variable

•Number of shin splints and knee problems runners have.

Constant Variables• Same runner

• Distance run per day

• Length of time tested (1 month)

• Size of shoe

Control Group• Nike Shox

(Any type you think of as “normal”)

Experimental Group• Nike Air

• Asics Gel

• Addidas Running Shoe

Treatment DescriptionControl Group 1 Group 2 Group 3

Nike Shox Nike Air Asics Gel Addidas Running

Shoe