INDIANAPOLIS -- With thousands of children bullied at school each day, experts said it's key that parents know the signs for which to look.

The National Education Association reports that more than 160,000 children miss school every day out of fear of an attack or intimidation by other students, 6News' Stacia Matthews reported.

While bullying can take many forms, experts said some of the signs are unmistakable -- fear, anxiety, dropping grades and changes in habit.

"Watch for their behavior. Their personality is changing, they are more withdrawn, perhaps more angry," said Carlabeth Mathias, a licensed clinical social worker.

Renee Earl, a nurse and mother of two, said she was worried she couldn't help her oldest son.

"His stomach was upset. He wasn't eating, and he wouldn't tell me what was going on," she said. "It's a helpless feeling when you can't protect your son."

Eventually Earl said she learned her son was being bullied.

"It was very disturbing, very disturbing," she said.

Mathias, who has counseled both victims and bullies, said she believes the problem is becoming more prevalent due to cell phones and the Internet.

The American Medical Association found that 85 percent of school children witness bullying, but that 90 percent of those students don't believe grown-ups will do anything about it.

Mathias said it's up to adults to set the tone that bullying will not be tolerated.

"When schools can create an atmosphere where it's not only accepted, but expected to report bullying and adults take action, then we can decrease bullying," she said. "If we give the bystander some appropriate skills to intervene, we can become a huge force of power to stop bullying."

Mathias said that includes reporting the problem until results are achieved.

6News will have a series of stories this week addressing the issue of bullying among children. We will host a Call 6 phone bank with experts on hand to answer your questions about bullying on Thursday from 5 to 7:30 p.m.