Question

practice: experimental design
read each scenario and answer the questions to the right.
maggie loves fresh brownies, and her grandma told her if she places a piece of bread in the storage container with the brownies, the brownies will stay fresh and moist longer. maggie decides to test this idea. she bakes a batch of betty crocker brownies. she places 6 brownies in 6 individual tupperware containers. each brownie is the same size and placed in the same location. she adds a piece of bread to three of the brownie containers, and leaves the other three alone. each day for 3 weeks she measures the moistness of the brownies, and records her results.

1. independent variable:
2. dependent variable:
3. hypothesis:
4. control group:
5. experimental group:
6. constants:

alex wants to grow some flowers for his wife, but isn’t sure which flowers will grow best in the soil in their yard. he goes to lowe’s and buys hydrangeas, roses, daisies, and tulips. he sections off the soil into four equal parts and plants each type of flower in their own section. all flowers receive the same amount of sunlight throughout the day and he waters them all the same amount and at the same time daily. he records the growth of the flowers once a week for a month.

1. independent variable:
2. dependent variable:
3. hypothesis:
4. control group:
5. experimental group:
6. constants:

abbey always gets zits on her chin and she can’t figure out the best method to get rid of them. she decides to test several products to see which clears her face up fastest: washing with soap and water, washing with an acne face wash from the pharmacy, and washing her face with organic oils. for one week she just washes her face with water. the next week she washes every day with soap and water. the following week she uses the acne wash, and the last week she uses the organic oils. each week she records the number of zits she has on her chin at the end of the day.

1. independent variable:
2. dependent variable:
3. hypothesis:
4. control group:
5. experimental group:
6. constants:

jenny loves to chew gum, but hates losing the flavor. she normally chews juicy fruit, but she wants to know if there is another type of gum that holds the flavor longer. she buys 4 different packs of gum, one of them being her normal juicy fruit. every day after lunch she picks one piece of gum and chews it until it loses flavor. she times how long it takes for the gum to lose flavor, and records the time. she chews the same type of gum every day until she has used up the pack, and finds an average time for how long the flavor lasted. then she starts chewing a new type of gum, and continues until all 4 types have been tested.

1. independent variable:
2. dependent variable:
3. hypothesis:
4. control group:
5. experimental group:
6. constants:

Explanation:

Scenario 1 (Maggie and brownies)

1. The independent variable is what is being changed, which is the presence of bread.
2. The dependent variable is what is being measured, which is the moistness of brownies.
3. A hypothesis could be: If bread is placed with brownies, the brownies will stay moist longer.
4. The control group is the brownies without bread.
5. The experimental group is the brownies with bread.
6. Constants are size of brownies, location, type of brownies, etc.

1. The independent variable is the type of flower.
2. The dependent variable is the growth of flowers.
3. A hypothesis could be: Different types of flowers will grow differently in the same soil conditions.
4. There is no clear - cut control group as all are different flower types being tested, but if we consider one for comparison, it could be one type of flower (e.g., hydrangeas).
5. The experimental groups are roses, daisies, tulips (along with hydrangeas if hydrangeas is considered control).
6. Constants are amount of sunlight, amount of water, time of watering, soil type.

1. The independent variable is the face - washing method.
2. The dependent variable is the number of zits.
3. A hypothesis could be: Different face - washing methods will affect the number of zits on Abbey's chin.
4. The control group is washing with water only.
5. The experimental groups are washing with soap and water, washing with acne face wash, washing with organic oils.
6. Constants are time period (one week per method), Abbey's skin type, time of day of washing.

Answer:

1. Presence of bread
2. Moistness of brownies
3. If bread is placed with brownies, the brownies will stay moist longer
4. Brownies without bread
5. Brownies with bread
6. Size of brownies, location, type of brownies

Scenario 2 (Alex and flowers)