The following is a letter by Srila Prabhupada to his disciple Rupa Vilasa dated 18 November, 1972 instructing that kids should be disciplined with love rather than force.
My dear Rupa Vilas,
Please accept my blessings. I beg to acknowledge receipt of your letter dated October 28, 1972, and I have noted the contents with care. I am very glad to learn that the children at Gurukula school are making good progress in their Krishna Consciousness education, that is very good news. Yes, if we simply train them properly they will come out just to the highest standard of Vaisnava devotee. And what is that training? Simply they should be engaged in such a way that they are somehow or other remembering Krishna at every moment, that’s all. It is not something mechanical process, if we force in such a way they will come out like this, no. We are persons, and Krishna is a Person, and our relationship with Krishna He leaves open as a voluntary agreement always, and that voluntary attitude—Yes, Krishna, I shall gladly co-operate whatever you say—that ready willingness to obey is only possible if there is love. Forcing will not make me agree. But if there is love, oh, I shall gladly do it. That is bhakti, that is Krishna Consciousness. So similarly, if we train children by developing and encouraging their propensity to love Krishna, then we shall be successful in educating them to the topmost standard. Then they shall always very happily agree to do whatever you ask them. So I have heard that there has been some beating with sticks on the children. Of course I do not know, but that should not be. You may show the stick, threaten, but better art is to somehow or other, even by tricking them, avoid this matter of force and induce them to obey out of loving spirit. That is success of disciplinary method.
Hoping this meets you in good health.
Your ever well-wisher,
A.C. Bhaktivedanta Swami