Question

identifying independent and dependent variables in experiments physical science identifying independent & dependent variables goal: to demonstrate student understanding of independent and dependent variables procedure - part i: identify the dependent and independent variable in each of the eight investigations below. remember the following definitions: independent variable the factor controlled (or changed) by the experimenter. this might also be described as the change that i, the experimenter, makes on purpose. it is sometimes called the manipulated variable. dependent variable the factor (or result) which changes because of what the experimenter does. the dependent variable is the change that occurs because of what the experimenter does; it gets changed by the independent variable. it is sometimes called the responding variable. it usually is measured in some manner. 1. what is the effect of scary movies on pulse rate? a. independent variable: b. dependent variable: 2. what is the effect of heat on ice melting? a. independent variable: b. dependent variable: 3. what is the effect of different types of oil on the amount of time it takes for the gears to reach a temperature of 30°c? a. independent variable: b. dependent variable: 4. what is the effect of higher levels of calcium on dendrite synapse relay time? a. independent variable: b. dependent variable: 5. which restaurant has the least amount of escherichia coli (bacteria) in their rice. a. independent variable: b. dependent variable: 6. the most expensive air freshener will kill the least amount of bacteria? a. independent variable: b. dependent variable: 7. what is the effect of trajectory angle on distance traveled? a. independent variable: b. dependent variable: 8. increased levels of pollution will increase the number of mutations in frogs. a. independent variable: b. dependent variable: 9. sodium chloride will dissolve the fastest in water at a temperature of 100°c. a. independent variable: b. dependent variable: 10. listening to jazz music will increase science test grades. a. independent variable: b. dependent variable: 11. longer school days will result in improved student grades. a. independent variable: b. dependent variable:

Explanation:

Step1: Recall independent - dependent variable definitions

Independent variable is manipulated, dependent variable responds to the change in independent variable.

Step2: Analyze each investigation

1. Effect of scary movies on pulse rate

a. Independent variable: Watching scary movies
b. Dependent variable: Pulse rate

2. Effect of heat on ice melting

a. Independent variable: Application of heat
b. Dependent variable: Ice - melting (amount or rate of melting)

3. Effect of different types of oil on gear - heating time

a. Independent variable: Type of oil
b. Dependent variable: Time for gears to reach 30°C

4. Effect of higher levels of calcium on dendrite synapse relay time

a. Independent variable: Level of calcium
b. Dependent variable: Dendrite synapse relay time

5. Restaurant - E. coli investigation

a. Independent variable: Restaurant
b. Dependent variable: Amount of E. coli in rice

6. Air - freshener and bacteria investigation

a. Independent variable: Cost (price) of air - freshener
b. Dependent variable: Amount of bacteria killed

7. Effect of trajectory angle on distance traveled

a. Independent variable: Trajectory angle
b. Dependent variable: Distance traveled

8. Effect of pollution on frog mutations

a. Independent variable: Level of pollution
b. Dependent variable: Number of mutations in frogs

9. Sodium chloride dissolution in water

a. Independent variable: Temperature of water (100°C)
b. Dependent variable: Dissolution rate of sodium chloride

10. Effect of jazz music on science test grades

a. Independent variable: Listening to jazz music
b. Dependent variable: Science test grades

11. Effect of school - day length on student grades

a. Independent variable: Length of school day
b. Dependent variable: Student grades

Answer:

1.
a. Watching scary movies
b. Pulse rate
2.
a. Application of heat
b. Ice - melting (amount or rate of melting)
3.
a. Type of oil
b. Time for gears to reach 30°C
4.
a. Level of calcium
b. Dendrite synapse relay time
5.
a. Restaurant
b. Amount of E. coli in rice
6.
a. Cost (price) of air - freshener
b. Amount of bacteria killed
7.
a. Trajectory angle
b. Distance traveled
8.
a. Level of pollution
b. Number of mutations in frogs
9.
a. Temperature of water (100°C)
b. Dissolution rate of sodium chloride
10.
a. Listening to jazz music
b. Science test grades
11.
a. Length of school day
b. Student grades