Also, don’t overlook these:

• definition vs. declaration
• the preprocessor: #define, conditional compilation, #include
• arrays and const
• struct, union, enum, and typedef
• the more commonly-used standard libraries: stddef.h, stdio.h, string.h, stdlib.h
• the different uses of static

Some more advanced topics for later:

• extern
• variadic functions
• long jumps

Also of practical help when teaching memory management: explain the meaning of “segmentation fault” and “bus error” — your student(s) will be seeing a lot of these! ;-)

Hope that helps,