With a bow to Virginia's tourism industry, the House of Delegates voted yesterday to make permanent a law to keep Virginia's public schools from opening until after Labor Day.

Sponsors have argued that state amusement parks and tourist resorts need to be able to hire high school students to the end of the summer season and that pre-Labor Day school openings interfere. Opponents object to the state's usurping local school board authority to decide when schools should open.

"Why do we have school boards?" one opponent asked the sponsor, Del. Alson H. Smith Jr. (D-Winchester). "Sometimes I wonder," retorted Smith, getting a laugh.

Del. Mary A. Marshall (D-Arlington), in supporting the bill, argued that a major point of education is to "let the children learn about the world around them" and that working in the summer encourages that.

An opponent, Del. John G. (Chip) Dicks III (D-Chesterfield), objected that the bill had nothing to do with education and would give college students, who often get out in May, a head start on high school youths. Del. Harry R. Purkey (R-Virginia Beach) said: "I can't emphasize enough how important this bill is to our area."

The measure got out of committee on a 10-to-9 vote. The House still must take a final, normally routine, vote on the bill before it would go to the Senate.