My teenage son Karl became withdrawn  after his father died . As a single parent . I tried to do my best to talk to him . But the more I tried , the more he pulled away . When his report card arrived during his junior year , it said that he had been absent 95 times from classes and had six falling grades for the year . At this rate he would never graduate . I sent him to the school adviser , and I even begged him . Nothing worked . One night I felt so powerless that I got down on my knees and pleaded for help . "Please God ,I can't do anything more for my son .  I'm at the end of my rope . I'm giving the whole thing up to you ." I was at work when I got a phone call . A man introduced himself as the headmaster . "I want to talk to you about Karl's absences ." Before he could say another word , I choked up and all my disappointment and sadness over Karl came pouring out into the ears of this stranger . "I  love my son but I just don't know what to do . I've tried everything to get Karl to go back to school and nothing has worked . It's out of my hands . "For a moment there was silence on the other end of the line . The headmaster seriously said , "Thank you for your time", and hung up . Karl's next report card showed a marked improvement in his grades . Finally , he even made the honor roll .In his fourth year , I attended a parent-teacher meeting with Karl . I noticed that his teachers were astonished at the way he had turned himself around . On our way home , he said , "Mum, remember that call from the headmaster last year ?" I nodded . "That was me . I thought I'd play a joke but when I heard what you said , it really hit me how much I was hurting you . That's when I knew I had to make you proud ." What is the main idea of this passage ?
Children in single-parent families often have mental problems . Mother's love plays an important role in teenagers' life . Being understood by parents is very important to teenagers . School education doesn't work without full support from parents .