Train to be a teacher. This is the best way to affect teaching and learning in a primary school, as you will be the one interpreting and implementing the syllabus. However, you will be limited to affecting learning in only one school. To become a primary school teacher in the UK, you will need a bachelor's degree, followed by a PGCE. In the United States, you'll need to earn a bachelor's degree in education.
Become a primary school governor. This is a very effective way to micro-manage the teaching and learning methods at a particularly primary school. Primary school governors must be elected in a similar way to members of the school board in the U.S. School governors and school board members have genuine authority to affect the learning curriculum within primary schools.
Attend parent teacher meetings and conferences. This is an effective way to make sure the teaching methods in your local primary school are working, if you do not have the time or inclination to become a teacher or governor. Parent teacher conferences are more common in the United States, but there is a parent teacher meeting every semester in the UK.