Reising, and Cook (1993) identified five options teachers typically use when implementing a co-teaching model. As teams progress through these 5 types, it is important to remember these types are hierarchical across three variables. First, as you move down the continuum of models, more and more planning time together is needed. Second, as you progress in the models, teachers need an equal level of content knowledge to make the model work effectively. This equality of content knowledge can be the greatest barrier to team teaching at the secondary level. Third, as you move down the continuum, teachers must share the same philosophy of inclusion and have a level of trust and respect. Typically this level of trust and respect has to be built over time, which also is another reason it is sometimes difficult to team teach at the secondary level or in larger schools, if there is not consistency over time in building team support. Key aspects of each type of co-teaching are provided below