For Tristen McKenna, the path was clear — he would become a welder when he graduated from high school.”My family never pushed for college,” said McKenna, a senior in Arizona’s foster care program. “They wanted me to go to a trade school — not college.”But last week, McKenna was one of 20 teens who participated in an immersive STEM program at Arizona State University, and it may have just changed the trajectory of his life.