Book & CD. This new enhanced edition of Subtraction Unplugged pairs the audio CD (teaching subtraction facts with minuends to 18) with a workbook filled with activities and exercises reinforcing what has been learned in the songs. While the focus of this learning kit is the teaching of subtraction, supporting activities also cover a variety of strands of the new Common Core Curriculum for Mathematics including: pattern recognition, dates, time, fractions, doubles, shapes, coordinates, reading graphs, ordinal numbers, Roman numerals, temperature and money.