Activating and acquiring schema are 2 different things altogether.  Activating schema is the ability to make a connection to a preexisting experience of knowledge previously developed at one time or another.  Acquiring schema requires an experience or a clear, defined explanation of what we want the student to interpret.  We cannot expect students to understand concepts that they have never approached or experienced.  It is important we create an environment for opportunities to provide visuals and explanations of new concepts and vocabulary in order for students to comprehend literature they read.  As an ESL teacher, I take every opportunity during read alouds to encourage conversation to make connections.  During these conversations is when I discover whether the students have an understanding of the concept or if it is necessary to further go into detail so that they may acquire schema from activating prior schema.