Selectmen tabled a vote Tuesday on whether to put a Proposition 2½ override request for education funds before voters. Town Manager Dan Morgado has proposed a budget for the school district of just over $51 million for next fiscal year, but the School Committee is requesting $54.2 million, and town officials are discussing whether to ask residents to approve a property tax increase to cover the difference. The School Committee says its budget would add seven teaching positions to help deal with overcrowding, and would include such cost-saving measures as eliminating some technology upgrades and increasing some fees paid by parents. Morgado’s spending plan would require laying off 21 teachers. He said Wednesday that the town will continue to review its finances, and he declined to say if or when selectmen might vote on the override question. A Finance Committee hearing on the budget is scheduled for Thursday at 7 p.m. in Town Hall. Residents have turned down the last three requests for tax increases to provide more money for the schools.