School officials said district policies restricted them from sharing information.
"We did not know that he was charged formally with lewd acts, this morning we heard," said district two superintendent Alma Sanchez. "When we hear that, of course we can tell."
Parents said they didn't understand how the school had no knowledge of Chapel's charges.
"It's just alarming and concerning because if the school district is not gonna be the one responsible and not take the responsibility and stop blaming it on 'policies' and other things that they can't do, instead of finding a solution to what they can do," said parent Darlene Villa.
According to court documents, the investigation involved six children but the district attorney only filed charges for alleged crimes against four victims, and at least one of them is a student at Telfair.
That young girl told detectives Chapel picked her up by her legs during class and kissed her on her neck and stomach.
One parent, who did not want to be identified, said her daughter told her the 50-year-old often tried to get kids to hang out with him in his classroom to eat candy and popcorn during lunch and recess.
School officials said Chapel was removed from the school last April when the investigation began.
Chapel, 50, taught third grade at Telfair Avenue Elementary School in Pacoima. He is charged with 16 felony counts, including lewd acts on a child under 14 years old by force, continuous sexual abuse of a child and oral copulation. Chapel pleaded not guilty to all charges.
Chapel is accused of sexually abusing three girls and one boy during the 2010 school year. It's unknown whether the alleged incidents happened on or off campus.
Chapel was arrested in October and remains incarcerated on $2.2 million bail. He's scheduled for a February 21 preliminary hearing.
Some parents are angry about not receiving notification from the school sooner.
"The police conduct investigations, we run schools. When they said in this case, just like in other cases, that there is to be no discussion and no notification, we follow that," said LAUSD Superintendent John Deasy. "So that they may conduct an investigation, get evidence that's not tainted to potentially put someone behind bars so they are never put back in the classroom again."
"It's really devastating learning about everything that is going on at other schools," said parent Giselle Garcia. "You think you are going to trust your teacher, but look at what happens."
The LAUSD has been at the center of a child sex abuse scandal. Last week, two teachers from Miramonte Elementary School in South Los Angeles were arrested on sex abuse charges.
Mark Berndt, 61, was charged with 23 counts of lewd acts on children ages 6 to 10. He's accused of taking photos showing children blindfolded with cockroaches on their faces and spoons full of semen in front of their mouths.
Martin Springer, 49, was arrested after two girls said he had fondled them in class in 2009. One of the girls later decided to withdraw the accusation. Springer was released on bail Friday.