My daughter went to a dual immersion program K-12 and is bi-lingual. I'm not, but we thought it important enough that we made the choice for her. The research at the time said that if you did it for 7 years, you have the language for life. So after middle school, we told her she could drop it (it becomes and elective in high school). Well, she wanted to continue on and got the endorsement as well.