Members conducting tuition Classes in their flats in housing societies is quite common feature and the management is really at a loss to handle it properly without creating ill-will with in otherwise harmonious environment.
where a flat Owner seeks prior permission to use the flat for tuition classes it will be extremely difficult to refuse except on the ground that the proposed classes would pose serious threat to security and peace, excessive engagement of the lift which may cause a grave inconvenience to the residents, as also higher running and maintenance expenses of lift, parking problems, where classes are proposed to be run as a professional activity by a member giving on rentals to a commercial organization etc. The managing committee would be well advised to put it up before the members in the general body meeting as the managing committee does not have an express/implied power under any Bye-law to consider such request and decide. The list of powers of the managing committee in Bye-Law No 139, (Model 2001/2009) or 138 (Model 2014) does not contain any power to allow change of the use of any flat not mentioned in the Allotment letter. But the bye law does not seem to confer the power on the managing committee to grant permission.
In any case it may not be legal to run tuition classes on a commercial basis within the flats.
You may have to look for a place outside for conducting the tuition classes before the issue develops into a big problem