can be tricky.  If your students find this transition very difficult, one strategy you can employ is to review lessons shortly after you have moved on.  For example, you could cover Lesson 15 and 16, then review Lesson 15 thoroughly before you begin Lesson 17.  Then you can review Lesson 16 before moving to 18. After Lesson 20, before moving on to Part Two of the manual, you could review Lessons 15, 16 and 18 again.  Most students in the Stevenson Program will not need this degree of review, but it useful for those who need it, and it will make subsequent material easier.