Level 2 Subtraction is one of the most challenging books in the Level 2 range because the student is required to confront the intricacies of subtracting negatives from negatives.
Terminology is key in understanding this process, and the traditional 'a minus minus a minus equals a plus' explanation is confusing and counterintuitive. "WHY does a minus minus a minus equal a plus?!" is a question many students have asked, and most have contemplated asking before giving up on the whole idea and doing their best to get by on wrote learning.
It is best understood by using A.F.L. Newberry's Balloon In A Vacuum explanation. If a positive is a single unit helium balloon which will cause lift, and the negative is a single unit sandbag which will cause drop, then when you take away (NOT "minus" which is a confusing double entendre when it is least needed) a negative you create lift, as you would if you drop a sandbag off the side of a hot air balloon. (Taking care there are no pedestrians below of course.)
This book contains:
- 20 Exercises
- 2,400 questions
- x2 performance graphs
- x30 10mm personal best and goal achieved stickers
- x 32 30mm ANT, Gold, Silver, and Bronze Stickers.
To see the stickers, watch this video: