physical science semester 1 review
unit 1
1. in any experiment, what is the definition of an…
a. …independent variable?
b. …dependent variable?
c. …control variable?
2. for an experiment to be valid…
a. …does it need a hypothesis?
b. …how many things should be changed at a time?
c. …does it need to have control variables? why or why not?
3. every experiment has a hypothesis.
a. what is a hypothesis?
b. what makes a hypothesis valid?
c. what is a good format for a hypothesis?
4. for an experiment designed to test the following hypothesis, identify the variables.
hypothesis: if students ask 2 questions per class period, then they will score better on the test than who ask no questions, because they get a better understanding of the material.
independent variable: dependent variable: control variable:
5. pat does an experiment in which he takes 3 corn stalks, he gives each stalk a different amount of
2 weeks, he measures the height of the stalks.
a. what is the independent variable?
b. what is the dependent variable?
c. what are 3 control variables?

Question

physical science semester 1 review
unit 1
1. in any experiment, what is the definition of an…
   a. …independent variable?
   b. …dependent variable?
   c. …control variable?
2. for an experiment to be valid…
   a. …does it need a hypothesis?
   b. …how many things should be changed at a time?
   c. …does it need to have control variables? why or why not?
3. every experiment has a hypothesis.
   a. what is a hypothesis?
   b. what makes a hypothesis valid?
   c. what is a good format for a hypothesis?
4. for an experiment designed to test the following hypothesis, identify the variables.
   hypothesis: if students ask 2 questions per class period, then they will score better on the test than who ask no questions, because they get a better understanding of the material.
   independent variable:  dependent variable:  control variable:
5. pat does an experiment in which he takes 3 corn stalks, he gives each stalk a different amount of
   2 weeks, he measures the height of the stalks.
   a. what is the independent variable?
   b. what is the dependent variable?
   c. what are 3 control variables?

Accepted Answer

### Question 1
#### Part a
# Brief Explanations:
An independent variable in an experiment is the factor that is deliberately changed or manipulated by the experimenter to observe its effect on another variable. It is the cause in a cause - effect relationship within the experiment.
# Answer:
The independent variable is the factor that the experimenter changes or manipulates to see its effect on the dependent variable.

#### Part b
# Brief Explanations:
A dependent variable is the variable that is being measured or observed in an experiment. Its value depends on the changes made to the independent variable.
# Answer:
The dependent variable is the variable that is measured or observed and its value depends on the independent variable.

#### Part c
# Brief Explanations:
A control variable is a variable that is kept constant throughout an experiment. This is done to ensure that any changes observed in the dependent variable are only due to the changes in the independent variable, and not due to other factors.
# Answer:
A control variable is a variable that is held constant during an experiment to prevent it from influencing the results.

### Question 2
#### Part a
# Brief Explanations:
For an experiment to be valid, having a hypothesis is important. A hypothesis is a testable prediction or statement that guides the experiment. It gives a clear direction to the experiment by stating what is expected to happen, so that the experiment can be designed to either support or refute it.
# Answer:
Yes, an experiment needs a hypothesis. A hypothesis provides a testable prediction that guides the experimental design.

#### Part b
# Brief Explanations:
In a valid experiment, only one thing (the independent variable) should be changed at a time. If multiple variables are changed simultaneously, it becomes impossible to determine which variable is responsible for the observed changes in the dependent variable. This is the principle of controlling variables to ensure a fair test.
# Answer:
Only one thing (the independent variable) should be changed at a time.

#### Part c
# Brief Explanations:
An experiment needs control variables. Control variables are necessary because they keep other factors constant. If other factors are not kept constant, they could affect the dependent variable, and we would not be able to attribute the changes in the dependent variable solely to the independent variable. This ensures that the experiment is a fair test and the results are valid.
# Answer:
Yes, an experiment needs control variables. They are needed to keep other factors constant so that the effect of the independent variable on the dependent variable can be accurately determined.

### Question 3
#### Part a
# Brief Explanations:
A hypothesis is a proposed explanation or prediction for a phenomenon or a set of observations. It is a statement that can be tested through experimentation or further observation. For example, in a plant growth experiment, a hypothesis could be "If plants are given more sunlight, then they will grow taller."
# Answer:
A hypothesis is a testable prediction or proposed explanation for a phenomenon.

#### Part b
# Brief Explanations:
A hypothesis is valid if it is testable and falsifiable. It should be based on existing knowledge or observations, and it should be possible to design an experiment or make observations that can either support or refute the hypothesis. Also, it should be a clear and specific statement, not a vague or untestable claim.
# Answer:
A hypothesis is valid if it is testable, falsifiable, clear, specific, and based on prior knowledge/observations.

#### Part c
# Brief Explanations:
A good format for a hypothesis is an "If - then - because" statement. The "If" part describes the manipulation of the independent variable, the "then" part describes the expected change in the dependent variable, and the "because" part provides a rationale (based on scientific reasoning) for the prediction. For example, "If a plant is watered with fertilizer - enriched water (independent variable), then it will grow faster (dependent variable) because the fertilizer provides essential nutrients (rationale)."
# Answer:
A good format for a hypothesis is an "If [independent variable is manipulated], then [dependent variable will change] because [rationale based on science]."

### Question 4
# Brief Explanations:
- **Independent variable**: The independent variable is the factor that is changed by the experimenter. In the given hypothesis, the number of questions asked per class period (2 questions vs. no questions) is what is being manipulated. So the independent variable is the number of questions asked per class period.
- **Dependent variable**: The dependent variable is what is being measured. Here, the test score is what is being measured to see if it changes based on the number of questions asked. So the dependent variable is the test score.
- **Control variable**: Control variables are factors that are kept constant. In this experiment, factors like the same class material, same test, same teaching method, same amount of study time outside of class (for students) could be control variables. For example, the class material should be the same for all students so that it does not affect the test score independently of the number of questions asked.
# Answer:
- Independent variable: Number of questions asked per class period
- Dependent variable: Test score
- Control variable: Factors like class material, test, teaching method (any factor kept constant to ensure a fair test)

### Question 5 (assuming the missing part is "water" as it is a common experiment with corn stalks and different amounts of water)
#### Part a
# Brief Explanations:
The independent variable is the factor that is manipulated by the experimenter. In this corn stalk experiment, the amount of water given to each stalk is being changed (different amounts for each stalk). So the independent variable is the amount of water given to each corn stalk.
# Answer:
The independent variable is the amount of water given to each corn stalk.

#### Part b
# Brief Explanations:
The dependent variable is what is being measured. Here, the height of the corn stalks is being measured to see how it changes based on the amount of water given. So the dependent variable is the height of the corn stalks.
# Answer:
The dependent variable is the height of the corn stalks.

#### Part c
# Brief Explanations:
Control variables are factors that are kept constant. For the corn stalk experiment, factors like the type of corn stalk (same variety), the amount of sunlight they receive, the temperature of the environment, the type of soil they are planted in should be kept constant. For example, if different corn stalks are exposed to different amounts of sunlight, it would be difficult to say if the change in height is due to water or sunlight. So three control variables could be: type of corn stalk, amount of sunlight, and temperature.
# Answer:
Three control variables could be: type of corn stalk, amount of sunlight, and temperature (any three factors kept constant to ensure a fair test).

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Question 1

Part a

Answer:

Part b