Cell Phones at Schools

Should we allow or ban cell phones at schools ?!! This is a main and popular topic at schools nowadays because of majority of guys who have cell phones, tablets, and all the staff. Some schools in many countries consider that cell phones are very beneficial for students while studying and many of others consider the opposite. If you are a teacher, or even a student, do you prefer to allow or to ban cell phones at schools and why ??!!

Disappearance of Files From Flash Memory (USB)

Problem:
The disappearance of files from the flash disk or external (External HDD) after suffering by viruses although they still exist (evidenced by the flash or disk space fills up).