On Friday, I was teaching students limits for the first time in Calculus. Understanding the notation of x -> a- versus x -> a+ can be confusing for students. After going over an example or two as a class, I could tell that some students were having trouble understanding the concept. I had anticipated this and had created an assignment in DeltaMath for my students to use. This was the first time students had to log in to DeltaMath this year and it was very easy for students to enter my teacher code and get started. Within ten minutes, each student had correctly answered ten questions like the following. Some students needed fifteen questions and individual instruction from me, but all students showed understanding of the concept of one-sided limits fairly quickly. Thank you DeltaMath!