I agree with every mom below and I love your contract idea for the ages of your kids. I have one thing that I would take OUT of your contract:
"I understand that my mom and/or step dad may take my phone away if I do not keep up my grades at school, keep my room clean and organized or if I am being disrespectful in any way".
I understand why you put that condition in there... but it inherently doesn't make sense.
I would only take away the phone if they are misusing the phone.
If you tie the PHONE to other behaviors then it's a punishment and in doing so you make life harder ON YOU (because then you can't get a hold of them if you need to). I am pretty big on natural consequences and having them fit the crime, rather than *punishments* that aren't related.
For example:
If they don't get good grades, the consequence is increased study time and/or a parent or tutor has to be more closely involved with their school work. They will naturally have LESS time to do fun things with their friends like going places or talking on the phone or texting or playing video games or watching TV. Because the most important thing they have to do as a student is learn the material. They still have their phone. You didn't *take it away* which will do nothing more than piss them off. YOU aren't inconvenienced by their bad grades.
If they don't clean their room.... now they have to miss out on something fun because their room is not clean and they have to have a clean room before they are able to do extra stuff. Sometimes mom gets involved in the clean room (which, really, is a fate almost worse than death to my daughter). it's important to have a clean room because it shows you respect your home, so right after homework and studying and practice for any commitments you have (piano, etc) all time is spent actively cleaning the room and if they can't do it on their own then I am in there giving them individual direction on what to clean (this I have only had to do about twice in her 12 years). The extra time spent in her room will naturally leave her less time on the phone. But you didn't take it away (other than she can't have it while she is cleaning) because that would inconvenience YOU.
Now, if they misuse the phone then all bets are off. But even then.... I would get them a phone that is programmed with numbers for people they CAN call in an emergency, and block everything else. Again.... misuse of the phone means no more calling friends or texting. it DOESN'T mean that they lose the way for YOU to communicate with them.
Make sense?