TEL AVIV, Israel (AP) _ Most Israeli schoolchildren stayed home today as their teachers went on a one-day strike to protest government plans to fire thousands of their colleagues.

The strike by one of the country's major teachers unions shut down all nursery schools, elementary schools and some high schools and colleges. There were no figures available of the number of students affected.

The walkout came after the Ministry of Education, which is seeking to cut its budget, refused a union demand to rescind the planned layoffs of some 3,500 teachers. Most Israeli teachers are paid directly or indirectly by the government.

The strike was called hours after publication of the unexpectedly high monthly inflation figures for April, which analysts agreed were mainly due to the failure to cut government spending.

April's cost-of-living index rose 19.4 percent, the highest monthly increase since wage and price controls were introduced last November. It brought the projected annual inflation rate to 320 percent, far exceeding the 200 percent target set by the government.

The government's economic policy-making forum was to convene in emergency session later in the day to discuss steps for arresting the economic decline.

Some of the proposals the six Cabinet members are expected to discuss are a freeze on new government contracts and an increase in the tax Israelis have to pay for leaving the country - from $150 to $400 or $500.

Such measures are designed to cut government spending and to absorb some of the public's buying power. Finance Minister Yitzhak Modai said the price surge in April means ''that there is too much buying power because people are willing and able to pay much more than real prices.''

Modai, speaking on Israel Radio, added that, ''We didn't cut the government budget as we should have and this is undoubtedly, if not the source of all evil, the main source of it.''

Israeli media dubbed the surprising April inflation rate ''the shock index.'' The daily Davar, which is owned by Peres' Labor Party, printed the 19.4 figure against a black backdrop across the top of its front page.