The advocates of full inclusion have the hidden agenda of promoting the adoption of progressive education practices. This is discovery learning and as parents you may be aware that students do not always push themselves as well as they might. You can see the progressive education model in full flower in the new participatory hands-on science museums. If you think this works to teach students well, go along with a group of students to such a museum. If you watch closely you will see that the students who are less capable play with things but don't read or pay attention long enough to understand what they are doing.
Advocates also mention multi-age grouping as a reform that can help deal with full inclusion.
The experiments prove that achievement is not helped if multi-age grouping is used to allow students to pursue their own ends or to let everyone work individually. By supporting full inclusion all the time, advocates hope to make it impossible to do direct instruction anymore. This will have a negative effect on achievement of all students. As has been stated earlier, one reason is because full inclusion of an extremely wide range of abilities into general education classrooms makes direct, systematic instruction nearly impossible. This has never produced high levels of achievement anywhere it has been tried.