Contract signing session etiquette for student coaches
I agree with earthling's answer and want to add to it. 

Since you have ten of them signing the same contract, there is nothing wrong with first explaining the contract to them as a group. Then, they can ask questions and benefit from the questions each of them asks. Tell them that they have until X date and Y time to sign the contract, that they have to sign it in front of you, and that they should feel free to ask you additional questions in private in case they did not want to ask a sensitive question at the group setting. 

Since these ten people will be presumably working together at the same job, there is nothing unethical about them all knowing that they have exactly the same contract.