Today’s bullies are much more sophisticated than the troublemakers of my youth. Victims, these days, don’t typically have a black eye or bloody nose; rather, they arrive home with internal scars that are unnoticeable to their parents and more emotionally damaging than a punch to the stomach.

One thing that has not changed over the years is the definition: Bullying is unwanted or aggressive acts among individuals of all ages that involve a real or perceived power imbalance. These acts are continually repeated over time and may range from physical harassment to complicated emotional abuse such as exclusionary tactics and rumor-spreading.

Unfortunately, thousands of children wake up every morning afraid to go to school because they fear their peers, and it is a problem that affects kids from kindergarten through senior year and beyond. Interestingly, some children–especially younger ones–often are unaware that they are hurting others, but older adolescents will employ intentional tactics aimed at devastating their targets.

As kids enter into kindergarten, they begin to understand social norms and rules but have difficulty grasping expectations. Playground cliques emerge as some kids enjoy sports, others play house, and many climb on the jungle gym. When an unwanted peer tries to join the fun, a popular member may belittle the unknowing child to the amusement of his friends. Enjoying this new-found attention, the group leader becomes a playground bully.

While it is true that the elementary years are a time of innocence for most, it also is the period where many begin to notice that others are different. Children begin to tease their classmates because of height, weight, interests, learning issues, clothes, hair color and other unimaginably unique qualities. Sadly, frequent teasing often leads to more than just tears as even first-graders can become anxious and depressed.

When kids enter middle school, bullying becomes more common and more vicious. Peer pressure, pack mentality and an undeveloped moral compass can foster unrelenting meanness toward others. Some even become overly aggressive to establish their social status. Furthermore, it can be developmentally difficult for a tween to understand that he has ‘crossed the line,’ resulting in some viciously persistent harassment. Victims become isolated, and it also is common for the abused to physically fight back.

The middle-school mentality still exists in high school, but teen bullies often engage in a much wider spectrum of abuse. Furthermore, different sexes use different strategies: Boys typically are more direct (physically and verbally), while girls are more indirect, often engaging in relational abuse such as crowding an unwanted individual out of a lunch spot. Technology also enters the picture and cyber-bullying provides the opportunity for 24/7 attacks. Unfortunately, older adolescents are less likely to report acts of aggression and more likely to suffer serious mental health concerns.

No matter the age, persistently bullied children suffer long-lasting biological effects as structural changes occur in the brain as a result of the emotional damage. Bullied children produce more stress hormones, which creates a constant awareness and sensitivity to potentially stressful situations. For this reason, students spend more time scanning the environment for threats, making it difficult to concentrate, learn and relax. Furthermore, many victims don’t properly develop the needed emotional and cognitive abilities to lead successful lives because they are continually worrying and protecting themselves from others.

If you feel your child is the victim of continual harassment, take appropriate action. Call or email your child’s homeroom teacher or principal, and objectively report your concerns. Find a therapist who has school experience. And, most important, involve your child in a new activity that introduces him to other kids with similar interests.

At some point during the educational years, most students will be victimized. A recent American Justice Department study indicated that 77 percent of all students have been bullied, and 15 percent of those kids reported that they were treated severely and suffered long-lasting effects. To ensure that your children stay safe, stay involved in their lives. Continually connect with your kids so they feel comfortable speaking to you about any topic.