Assembly is a low-level programming language for a computer, or other programmable device, in which there is a very strong (generally one-to-one) correspondence between the language and the architecture's machine code instructions.
Assembly provides a direct understanding of how code actually runs on computers, allowing for a strong understanding of computers and languages at a fundamental level.
Assembly would fit very well into a curriculum with an embedded component (say, the Arduino or the Raspberry Pi), allowing students to immediately connect their work with 'real systems'.
Pro Low Level - it's how the computer works
One of the best ways to learn how a computer actually works is to work your way up from lower level abstractions. Assembly, being only a level above machine code, is low enough level to make it clear how the computer is actually performing a computation, including code flow and loops, but high enough level to not be excessively tedious for the type of small projects that a student would do at the beginning of their first programming class. Use of an assembler with macros can stretch this even a bit further.
Pro Useful for embedded systems
A curriculum that involves an embedded component, such as an Arduino or a Raspberry Pi, can encourage students by allowing them to immediately connect their work with 'real systems'. Assembly is the ideal language for getting started with and understanding these devices, and since Assembly can be called from C, the code will still be useful if students move on to C later in the program.
Pro Uniform syntax
Assembly language syntax is relatively uniform, and so there's less room for a student to get confused by obscure characters, or miss some meaning implied by structure, such as with scoping rules, or call-by-name/value/reference semantics. While there may be a lot of mnemonics to look up, most work involves only a very small subset of them.
Con Difficult learning curve
Starting off as a beginner with assembly language could prove very daunting. I suggest learning a high level language first (e.g. C) to get a good grasp of programming - especially dealing with bits, bytes, numbers, accessing memory with pointers (which is why I suggest C).
Then once that person is comfortable writing C (or whatever high level language) programs, they would find moving to assembler a little less of a "What the hell?!!!" experience.