The most disheartening thing about recent racist incidents in the Philadelphia region was the involvement of teenagers. It was a bitter reminder that despite progress since the 1960s, children are still being brought up to hate.

But the rejection of hatred by students who were outraged by their peers' racism taught another lesson, that the future does not have to be a repeat of the past.

Washington Township High School students staged an all-day sit-in Thursday to show their disgust with a spate of racist, social-media messages exchanged by other students, most of them athletes. The messages led to a scuffle Wednesday between black and white students.

The protesters said they needed to get school officials' attention because this wasn't the first incidence of racism at the South Jersey school. "We wanted to make a statement that this is not OK. The students want change," said Kayla Webster, a junior.

Coatesville Area High School students similarly decided to show disdain for bigotry after schoolmates posted photographs on social media of pumpkins carved with a swastika and KKK. Hundreds of Coatesville students walked out of class Friday and marched around the school.

"This isn't something that we want to do," said senior Tyrel Bladen. "It's something we have to do." School officials organized a "Unity Event" after they heard about the planned protest, but students extended their walkout until the end of the school day to show they had acted independently.

There was also a racist incident at Quakertown Community High School in Bucks County. Racist insults were shouted at black cheerleaders from Cheltenham High School during an Oct. 6 football game at Quakertown.

School officials asked the Peace Center in Langhorne to develop a racial tolerance program for Quakertown students, which is an excellent idea. But the Cheltenham cheerleaders said adults also made racist comments. Who's going to make Quakertown parents take a tolerance class?

Quakertown Superintendent William E. Harner said his "heart was broken" when he heard about the racist taunts. But some of the offended Cheltenham cheerleaders said they didn't believe his apology was sincere. That's understandable. It's hard to have faith in adults when you know bigoted children form most of their opinions at home.

Adults must send a strong message to their children that prejudice in any form is wrong. That's what some parents did in Montgomery County's Red Hill, Pennsburg, and East Greenville communities when residents found fliers in their mailboxes with racist, white supremacist, and anti-Semitic messages, drawings, and quotes from Adolf Hitler.

Steve Grourke and his wife Erin said the fliers led them to start talking to their four children, ages 4 to 11, about racism. Donna Sattler and her husband are doing the same with their 13-year-old daughter. "We had a very honest discussion about what a Nazi is and what the ideology represents," Sattler said, "and that the USA fought in a war so this exact type of thinking should not be tolerated in 2017."

One day, parents won't have to teach their children about prejudice, but that day is not today.