I believe the one thing that is critical and non-negotiable in both teaching is that all students be provided with an equal opportunity to succeed. It is the teachers job to provide that opportunity, but it is the learners job to cease the opportunity.
Although some students may come in far below grade level, it is still possible for all students to achieve success when provided the right opportunities. Throughout this course, we have read and discussed various learning theories that imply methodologies and practices that can be applied to promote student learning. If teachers have students who are struggling due to a lack of motivation, the behaviorist theory can be applied in a sense where students recieve positive reinforcement whenever they complete an outcome as desired by the teacher. If the problem stems from a student who appears to be disengaged, the teacher can try integrating Gardner's multiple theories of intelligences to accomodate the students preferred learning style. In the case where a student is simply struggling to grasp a concept due to limited background knowledge, the teacher may want to start off by applying the connectivist theory in which the student is encouraged to corroborate with other students who may be able to enlighten the struggling student in ways in which the teacher wasn't.
All in all, there are so many approaches educators can take to ensure success in all students. As long as teachers acknolwedge that "one size does not fit all" they will be doing their students justice as they incorporate a multitude of theoretical approaches to meet the various needs of their students.