Specific classroom observations

I observed today in a classroom of 11th grade U.S. History students. The first period class consisted of an overwhelming majority of ELL students. I noticed that the same content was covered and in almost the same style. The instructor made few adjustments. the major difference was pace. The teacher took longer in explaining material and in covering vocabulary. I asked the teacher about the class. They explained to me that the administration was trying a new method of placing these students in one class. The teacher found that it was much harder to have the majority of the class be ELL students. It made me wonder what the best solution is for teaching ELL students...

Do we place them in a class together and work at their pace? Do we break them up into various classes and have them learn along with everyone else? I wonder if this instructor had changed his lesson plan slightly to try and cover the material using one of the ELL strategies would he have had a different result?