Amma Kanakku is all about Shanti, a single, hardworking, mother of a teenage daughter, played by Amala Paul . She belongs to the financially lower class and lives with her daughter Abhinaya in a slum like part of town.
For Shanti, it is her life’s dream to make her daughter an educated, capable member of the society so that she never has to struggle like her. But Abhi is super playful, rebellious and does not want to study at all. Abhi passes from 9th and goes to the 10th grade, which means the board exams.
Shanti is super worried about Abhi and her poor performance in Maths. When she conveys her worries to the person she works for as a maid, a Dr Nandini, played by Revathi, she suggests that maybe Shanti herself should commence her education again and in that way help her daughter pass.
So in a really unexpected twist, Shanti joins Abhinaya’s class as a student, much to the amusement of Mr Ranganathan, the Maths teacher, which is played by Samuthirakani. But this move from Shanti really sours the relationship she has with Abhi. As time goes on and Shanti becomes more and more popular among the students for her hardwork and dedication, Abhi decides to vanquish her mother in Maths. So a hilarious rivalry begins between the mother and daughter to see who will do better in the subject.
But in spite of all the planning, Abhi still refuses to focus and the rapport of the mother and daughter gets really strained. Whether Shanti finally manages to make Abhi understand about what she is going through to educate her and whether Abhi manages to ace the boards makes up for the rest of the tale.