What else can look like shyness in young students?

There are four possibilities, each much less likely than true shyness.  In close cases, a expert's opinion might be useful.  The four problems that might look like shyness are:
1.      Unidentified deafness. 
Consider this possibility if the student does not respond in any way to loud noises or someone calling her name behind her.  A teacher calling, “Lisa, stop!” behind Lisa while Lisa is walking will bring a behavioral response in a shy child but not a deaf one.
2.      Undiagnosed autism.
Consider this possibility if the student shows bizarre behavior such as hand flapping or repeating some other movement again and again, has frequent tantrums, or often makes unintelligible sounds. In general, shy children act normal other than when they are in specific social situations.
3.      Undiagnosed depression.
 Consider this possibility if the parents, when asked, say that the student usually acts or looks depressed or distressed at home.  Shy students usually look and act happy and confident at home.
4.      Unidentified speech delay.
 Consider this possibility if the students try to speak and joins the other children in activities and volunteers and lines up as fast as the others.  Shy students speak normally at home, so if the parents, when asked, say that the child does not speak clearly at home, the problem is more likely speech delay than shyness.