( HLN ) -- When Nelba Marquez-Greene lost her 6-year-old daughter in the Sandy Hook Elementary shooting in Newtown , Connecticut , she chose to cope with her loss in a unique way : by writing a letter . That letter , which addresses teachers and was published September 6 in Education Week , tells a story that will shake any parent to the core . Not powerless : What parents can do after Newtown . Marquez-Greene 's daughter , Ana Grace , was one of the 20 first-graders killed December 14 , when 20-year-old Adam Lanza arrived at the school with a rifle in hand . Six educators were also fatally shot by Lanza before he killed himself . `` While waiting in the firehouse that day to hear the official news that our daughter was dead , my husband and I made promises to ourselves , to each other , and to our son , '' Marquez-Greene writes . `` We promised to face the future with courage , faith , and love . '' Teachers lessons in heroism and healing . Marquez-Greene goes on to speak about the courage and bravery of teachers , marveling at how they could return to work after an event as traumatizing as the shooting . When Marquez-Greene asked her son 's teacher why she returned , she got an answer that made perfect sense to her as a parent . `` Because they are my kids , '' the teacher told her . `` And my students need me now more than ever . '' Marquez-Greene says that the courage of each teacher requires faith and deep love on their part . Her image of a hero , she tells us , is the everyday worker : the principal , school lunch worker , custodian , reading specialist , teacher or bus monitor . `` Real heroes do n't wear capes . They work in America 's schools , '' Marquez-Greene writes . Opinion : Above all , teachers do it for the kids . While Marquez-Greene , the mental health director for the nonprofit organization Sandy Hook Promise , admits that she `` almost lost her mind '' when she had to return her son back to the classroom , she said they sent him back because they did n't want him to be afraid . `` Parents are sending their precious children to you this fall , '' she writes to the teachers . `` Some will come fully prepared , and others not . They will come fed and with empty bellies . They will come from intact homes and fractured ones . Love them all . '' How Georgia school hero kept shooter calm .
Sandy Hook mom writes letter to teachers . `` My students need me now more than ever , '' one teacher told her . `` Real heroes do n't wear capes , '' Nelba Marquez-Greene writes .