About 220 elementary school students are taking a field trip to Clemson University today to learn more about engineering and science. National leaders link those disciplines to economic prosperity. Students from Clemson and Central elementary schools gather on the second floor of the Hendrix Student Center to work with Play-Doh, learn about robotics and build bridges out of gummy bears and toothpicks. The acronym “STEM” stands for science, technology, enginnering and math. Organizers of the Engineering Expo hope to spark an interest in students early on and that they will carry the enthusiasm through middle and high school, then to college. A recent study showed that the majors students choose have a big impact on future salaries. Four of the study’s top 10 highest-earning majors in terms of median salary are offered by Clemson’s College of Engineering and Science.