May 1, 1984

As one of the country's fastest-growing high-technology companies, the Data Switch Corporation is the kind of centerpiece for economic development that most small cities long to have. So the news that it is leaving Norwalk has not been easy to swallow. ''It's like a child growing up and moving out,'' Mayor William A. Collins said. ''Sadly, there is no way we could hold on to a company expanding that fast.''

A picture caption in Metropolitan Report April 23 with an article about New Yorkers at the Sackler School of Medicine in Tel Aviv misidentified the two students shown. They were Gay Lieberman and David Rosenberg.

THE professional organization of English teachers is offering its members modest grants to do their own research on classroom effectiveness instead of waiting for findings by experts in university ivory towers. The Research Foundation of the National Council of Teachers of English (N.C.T.E.) has responded to the current clamor for better schools by urging classroom teachers to join the reform movement as classroom- based researchers. Grants of $200 to $2,000 are being offered for any on-the-job research that will improve the way both teachers and children function in the classroom. The foundation has an annual awards budget of about $30,000. Grants are not applicable to the purchase of equipment, convention travel or research that is part of graduate degree programs. They may, however, be used for clerical help, research assistance and reproduction of the findings. Successful research is made avail able to other teachers through the council's publications.

An article in Business Day on Friday about a lawsuit over Costa Rican debt incorrectly described the preparation of the decision in the case. It was by a three-judge panel, with no author identified.

Senator Gary Hart said today that Walter F. Mondale, as Vice President, was part of an Administration that was ''weak,'' ''inept,'' ''uncertain'' and marked by ''days of shame'' in Iran. ''Walter Mondale now promises an America that can and will stand up for its vital interests,'' the Colorado Senator told an ebullient crowd of hundreds of students at Texas A&M University here. ''But Carter-Mondale actually gave us an America held hostage to the ayatollahs of the world.'' ''In national security as in domestic policy,'' he said, ''we must not leave the American people with a bleak choice in 1984 between two failed pasts - that of Ronald Reagan and that of the Carter-Mondale Administration.''