Sorting to Algebra Developing Mathematical Thinkers
Cross Number Puzzles P uzzles are not "dessert" for after the "real" work is done. Selected properly and introduced thoughtfully, they can be the real work. EDC
What am I supposed to do? What CAN I do?
Algebraic Ideas Breaking it up
What does the “thick line” do? 4
421
What does the “thick line” do? 42125
What about this way? 100
What about this way?
What about this way?
Kindergarten Sorters
4 + 5 = = 4 7 Addition and Subtraction From sorting to algebra Challenge: can you find some that don’t work? 5x + 3y = 23 2x + 3y = 11 Is there anything interesting about addition and subtraction sentences? 13 +=
Back to the very beginnings Picture a young child with a small pile of buttons. Natural to sort. We help children refine and extend what is already natural.
Back to the very beginnings Children can also summarize. “Data” from the buttons. bluegray large small
large small bluegray Abstraction If we substitute numbers for the original objects…
A Cross Number Puzzle Don’t always start with the question! st grade
Building the addition algorithm Only multiples of 10 in yellow. Only less than 10 in blue nd grade
Relating addition and subtraction nd grade
The subtraction algorithm = 6363 – 38 = 25
The subtraction algorithm = 6363 – 38 =
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus
Place Value Bonus = 832
Cross Number Puzzles and Multiplication
Developing a familiar multiplication algorithm
The algebra connection: adding = = = 7 3
The algebra connection: subtracting = = 4 6 += 4 2
The eighth-grade look 5x5x3y3y 2x2x3y3y x + 3y = 23 2x + 3y = = 3x3x0 x = 4 3x3x0 12 All from sorting buttons!
Algebra At the Core Kindergarten – Grade 5 Focus on underlying principles allows “two for the price of one” subtraction is un-addition division is un-multiplication Mastery of traditional algorithms Easier and more exciting to learn and explore More competently used
For more information about Cross Number Puzzles and Think Math! visit thinkmath.edc.org