1. Developing Algebraic Thinking
Murray Britt
University of Auckland Faculty of Education
Auckland February, 2005

3. a + b = a + (c + b – c) = (a + c) + (b – c) a – b = (a – c) + (c – b)39 40 28 1 27
a + b = a + (c + b – c)
= (a + c) + (b – c)
= 39 + (1 + 27)
= (39 + 1) + 27 7 2 98
100
107
a – b = (a – c) + (c – b)
107 – 98 = (107 – 100) + (100 – 98)

12. Counting All
4 + 3 =
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1 1 2 3 4 5 6 7
4 + 3

13. Advanced Counting = 6 5 4 3 2 1 34 28 29 30 31 32 33
34 - 6