This version of the activity is linked to google spreadsheet.
Refer to the link in the activity on how to set up your own copy of this activity and own copy of the google sheet.
The hints self review exercise for negative numbers is based upon the concept of zero pairs.
Note on conceptual representation of numbers using discs based on zero pairs:
Blue represent positve numbers : 6 - 3 (6 blue discs minus 3 blue discs)
Red represent negative numbers : minus 3 blue discs is converted to 3 red discs
ie - 3 = (-3)
So 6 - 3 = 6 + (-3)
= 3 + 3 + (-3)
= 3 + (3 - (-3)) zero pairs in brackets
= 3
