Invented+Strategies+For+Addition+and+Subtraction

= Invented Strategies For Addition and Subtraction =

Nicole 's class collected 652 cans for the recycling bin. On the way to the bin, 128 cans were lost. How many cans were put in the recycling bin?

Incremental
652 - 128 = ? 652 - 100 > 552 - 10 > 542 - 10 > 532 - 2 > 530 - 6 > 524

128 + ? = 652 128 + 500 > 628 + 20 > 648 + 2 > 650 + 2 > 652

Students join or separate in "chunks" or increments that make sense to them.

Combining Tens and Ones
652 - 128 = ?

600 - 100 = 500 50 - 20 = 30 2 - 8 = -6 (which means I still need to take 6 away) 500 + 30 - 6 = 524

Students deal with the different places (hundreds, tens, ones) and then combine them in the end.

Compensation
652 - 128 = ?

652 - 130 = 522 522 + 2 = 524

Students change or compensate a number to make it "friendly or easier" to work with. They then fix the answer in the end. (add or subtract the amount that was compensated.

More Examples: