At first I was really sceptical about this premise of this drama. What a silly idea: a mom whose daughter is being bullied dresses as a teenager and enrols in school to get to the bottom of it. And as young as Kim Hee Sun looks, no one could possibly mistake her as a teenager. But quite often when we watch dramas there's some kind of disbelief that we have to suspend. In "I can hear your voice" it's that the lead can hear your thoughts if he can see your eyes and there are plenty of other examples. I decided to watch because I have no problem suspending disbelief and I'm a huge Kim Hee Sun fan, I think she's brilliant and this drama is no exception. She has no business being THAT good at acting like a teenager - she's amazing and believable. The story is great, complex, fast moving for the most part and entirely believable. It's a bit slow in a few episodes in the middle, but that doesn't ruin anything. It tackles big issues like corruption, and high school bullying well and with feeling. All the acting was fabulous, everyone did a great job with complex and interesting characters. There was great personal development from everyone. Almost all the characters were likeable and by the end even some of the bad guys had my sympathy and i'm sure much of this was due to the brilliant performances put in as well as the well written characters. Watching Ji Hyun Woo play bumbling, ultra caring, teacher Park Noh Ah grow a backbone was so satisfying. He was such a great character played so well. Kim Yoo Jung as Oh Ah Ran and Ji Soo as Go Bok Dong were both brilliant. These are two young actors I'll follow closely. Both of their performances were nuanced and believable. Kim Hee Won as gangster Ahn Dong Chil was so wonderful, my feelings towards him changed slowly as he changed as a character, it really was an excellent performance. The standout, of course, was Kim Hee Sun. I really love how expressive she is without huge gestures, no screaming, over the top crying which is all too common for Korean "mom" actresses. I felt her pain when she hurt, I felt her exhilaration. I thought she was fantastic. All of the side characters were really well built characters and all of the actors put in good work to bring them to life. Han Gong Joo and her two stooges, and secretary Joo Ae Yeon had interesting stories, brilliantly portrayed Where this drama loses points is the same place most dramas lose points for me. An over-played, too evil bad guy (or two). I just can't believe their motivations because they're too bad. It happens so often and I'm so tired of it. In this drama it's extra jarring because all the other characters are so good, and all the other acting is wonderful. I wish writers would stop writing bad guys like this and hiring such bad actors to portray them. The music was used well in the right context. I think rewatch value for this is quite low, I can't imagine watching it again now that I know the resolution and have watched the plot play out. I highly recommend this drama. The story is solid, the acting is excellent. If you haven't already, give it a go.