# Ask an Expert: Dice probability

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### Dice probability

My son wants to do the dice probability experiment that is posted on this site. The problem is ...he needs to have a controlled, independent and manipulated variable. Does this experiment have all 3?

### Re: Dice probability

Hello there,

To start us off, here is an excellent page on Science Buddies describing how to identifying variables in your experiment: http://www.sciencebuddies.org/science-f ... evariables.

Your independent variable would be what you are changing or manipulating, while your dependent variable would be what you are observing as a consequence of changing your independent variable. As experts, we are encouraged to help you figure out your variables as opposed to directly telling you, but from what I can see, there are definitely independent and dependent variables in this experiment. Why don't you take a look at that link I sent you and at your experimental procedures and share what you think are the variables, and we can discuss whether they are correct or not?

Hope this was helpful. Please feel free to post back with additional questions or comments!

Best,

Connie

To start us off, here is an excellent page on Science Buddies describing how to identifying variables in your experiment: http://www.sciencebuddies.org/science-f ... evariables.

Your independent variable would be what you are changing or manipulating, while your dependent variable would be what you are observing as a consequence of changing your independent variable. As experts, we are encouraged to help you figure out your variables as opposed to directly telling you, but from what I can see, there are definitely independent and dependent variables in this experiment. Why don't you take a look at that link I sent you and at your experimental procedures and share what you think are the variables, and we can discuss whether they are correct or not?

Hope this was helpful. Please feel free to post back with additional questions or comments!

Best,

Connie

### Re: Dice probability

Thank you so much for your quick response. Thank you for the page on variables. My son has come up with what he thinks they are. He would like me to run them by you. He needs to have a controlled, manipulated and dependent variables in his experiment. For this experiment he believes that the controlled variable is rolling each dice combination 100 times, the manipulated variable us the number of sides on the dice, and the dependent variable is the sums of dice combinations. I think he's on the right track. I'm not sure if there are other controlled variables. When he presented this idea, his teacher questioned whether or not this experiment had all three and so that's why this has been such a struggle. Thanks again!

### Re: Dice probability

Hello there,

Great job figuring those out! That all sounds correct to me. Do other experts have anything to add?

Let us know if you have any further questions.

Best,

Connie

Great job figuring those out! That all sounds correct to me. Do other experts have anything to add?

Let us know if you have any further questions.

Best,

Connie

### Re: Dice probability

Hello. Connie has given you excellent advice. I would like to add on.

I think your son is on track with the independent and dependent variables. I would like for him to think about the controlled variable a little more. The purpose of a controlled variable is to keep something constant that, if not held constant throughout the experiment, could affect the outcome of the results. Rolling 100 times gives you your sample size, but that's not exactly a controlled variable. Changing the number of times you roll to 50 or 150 probably won't change the outcome.

Can your son think of some things that could affect the outcome? Here are some things to think about...not necessarily controls. Your son needs to decide whether they could affect the outcome. An experiment can have more than one controlled variable and usually does. The important point is regardless of what he chooses, he just needs to explain why he chose the controls to the judges.

- Amount of time you shake the dice before throwing?

- Person throwing the dice?

- Throwing left or right handed?

- Will the same dice be used or different dice?

- Throwing the dice from the hand or from a cup?

- Throwing across a floor (dice roll further) v. throwing into a confined space

If your son has further questions, be sure to write back. Good luck!

I think your son is on track with the independent and dependent variables. I would like for him to think about the controlled variable a little more. The purpose of a controlled variable is to keep something constant that, if not held constant throughout the experiment, could affect the outcome of the results. Rolling 100 times gives you your sample size, but that's not exactly a controlled variable. Changing the number of times you roll to 50 or 150 probably won't change the outcome.

Can your son think of some things that could affect the outcome? Here are some things to think about...not necessarily controls. Your son needs to decide whether they could affect the outcome. An experiment can have more than one controlled variable and usually does. The important point is regardless of what he chooses, he just needs to explain why he chose the controls to the judges.

- Amount of time you shake the dice before throwing?

- Person throwing the dice?

- Throwing left or right handed?

- Will the same dice be used or different dice?

- Throwing the dice from the hand or from a cup?

- Throwing across a floor (dice roll further) v. throwing into a confined space

If your son has further questions, be sure to write back. Good luck!

Deana

### Re: Dice probability

Wow. Thank you for your reply. My son actually just wrote it up last night and I had asked him to include more controlled variables ( because his rubric said to include all controlled variables and like you said many times there are more than one). He came up with rolling the dice in the same spot (floor) and using the same dice roller. Then I see your response this morning. I'm proud of him! Thank you to both of you that responded.

### Re: Dice probability

Excellent! Sounds like he is on track. Good luck, and be sure to write back if he has further questions.

Deana