In some countries like France, last-year high school students choose professions they are interested in and they visit corresponding companies/institutions for a week. There they can observe the everyday work and get an idea of the job.
An expansion of this system would be students throughout high school to visit jobs related to every class they take. For each course, it can be one day per year. For example, for mathematics, they can visit an engineering company, for physics they can visit a weather station, for physical education a sports team, for arts an artist. To find the places students can go, high schools can form connections with local companies or institutions.