Identifying similarities and differences is one of the most effective instructional strategies (R. Marzano).
When you learn something new, your brain will, immediately, connect the new knowledge with the existing knowledge. Teachers can support their students to make these connections by using graphic organizers or visual representations:
Comparing
Classifying
Creating Metaphors
Creating Analogies
Read more about Robert Marzano: http://gritineducation.com/marzano-over-effectieve-didactische-strategieen/