I'm currently teaching 6-9 right now and I have colleagues that are majoring in elementary teaching. I would say the number one thing they consider when wanting to switch majors is the age-level and maturity of the students this age. You can be placed anywhere from k-6 when majoring in elementary education. There is a huge developmental and behavioral gap between students in any of these grades/ages. So, my suggestion to you is definitely get a lot of experience with kids this age prior to committing to any degree. They can be wonderful, but kids this age range are also a lot to handle. You will also need mastery of a variety of subjects vs. in secondary ed you only need mastery of the subject you are teaching (at a higher skill level of course).