The best way is by preparing a parent/teacher agreement form as well as a Media Usage permission slip, also known as a "media release form". This allows not only for the student to use the technology but also for them to take an active part in it through pictures, video, or news/media releases of the student when applicable.
When you receive the forms back, screen-out the students who do not get permission to utilize the technology or use the Internet. This is a rare occurrence but it does happen. Differentiate for those students and ensure that you tell the parents that you are doing so.
The e-newsletter is perhaps the most consistent and valid method of communication. In it, you are able to "advertise" how you use technology in the classroom. You can post samples of student work, recommended websites for practice, academic support sites, and even interest sites for parents.
Along with the e-newsletter post the exact list of rules and expectations that you have posted in the classroom. This makes the parents understand what their children are actually doing. Moreover, ensure that this checklist is part of the agreement between teachers and parents regarding the use of the technology.
There are really two questions in one. First, how do teachers have better communication with parents is to realize that parents are not your students.
In all my years, the best practice is to learn that nothing you say or do will help the communication along or change the problems than making sure that you never speak down to a parent no matter what.
Do not allow them to control the conversation, manipulate you at the expense of their child and finally make the parent part of the solution rather than telling them how it is and what is and what is not going to happen.
The best advice is not to say you understand, that is condescending and standard. Tell them that you are on their side and ask them how you both can better work together for the good of the student.
Next, Ethical Technology and student use. Parents want their kids to have cell phones as a sense of security and control over their kiddos. Kids use technology is any form necessary without ethical concerns a majority of the time.
Let's be honest, technology is the world's greatest babysitter and entertainer. The question should be how we can help parents better understand that ethics may be generational. but safety crosses all generations.
What is or was ethical for the parent does not apply entirely to their child or the educator using technogy.
Teachers can be good communicator with parents by face to face meeting. Technology has no ethics, only the users. Parents and teachers are ultimately responsible for the ethics of children, no matter what they do unethical.