From Hindupedia, the Hindu Encyclopedia

vidyārambha (‘commencement of learning [of the alphabet]’) A child used to be sent to the guru- kula for education after the upanayana ceremony, generally at the age of seven. In the ancient days, the samskāra or sacrament of teaching the letters of the alphabet, perhaps, used to be conducted at the time of caula (rite of hair-cutting for the first time) itself, usually at the age of five. This sariiskāra, known as vidyā¬rambha or akṣarābhyāsa, is quite common even now. It is being performed even at the age of three or four. Orthodox tradition recommended the following procedure: fixing up an auspi¬cious day, preferably in the uttarāyaṇa (northern solstice) period; bathing and decorating the child; propitiation of the deities Gaṇapati, Sarasvatī, Nārāyaṇa, Lakṣmī, Bṛhaspati and the family deity; performance of a homa; teaching the alphabet to the child by first writing a mantra such as orh namassiddhāya and then the alphabet; honouring the teacher. Letters may be written on rice spread over a plate with the index finger. Later a slate and a suitable pen or chalk may be used.