You should carefully watch for signs of suicidal behavior if your child has recently:

Her father also shows signs of paranoia and other erratic behavior, she said.

You're both teachers, you're trained to look for signs of abnormal behavior in kids.

Music tells no stories, but it is a sign of human behavior.

In addition to being a sign of risky sexual behavior, the diseases themselves often make it far easier for someone to become infected.

Everywhere one looks, though, there are signs of potentially hazardous behavior.

He had no doubt it would come rushing in at the smallest sign of erratic behavior.

Look for signs of bullying behavior, such as creating mean images of another kid.

He showed no signs of strange behavior prior to the attack.

As stated above, physical contact is usually a sign of inexperience and/or dysfunctional behavior.