We begin studying addition, the simplest and most important operation. First we concentrate on adding numbers in the range 1-5, then we move on to the range 1-10. For this latter step, we need to introduce the names for the numbers 11-20. Unfortunately the English names for these are somewhat adhoc and not entirely logical, putting students at a disadvantage. An alternate numbering system is described. Finally we organize things into addition tables, and note some pleasant properties of these.