Math notes for 10/19

Multiplication:

You need to start out concretely, not through abstraction or memorization. It helps to start by teaching with arrays (more on that later, it's hard to post the diagrams on the blog!)

Younger students can use tiles and manips. for starters, but should be weaned off later.

Cindi diagrammed various methods of multiplication strategies. I can show you them later.

To multiply effectively, especially in algebra, you must remember the:

Order of Operations

Please (parentheses)

Excuse exponents

My x multiplication

Dear division

Aunt addition

Sally subtraction

Different strategies kids use to multiply:

Repeated Addition

43 x 6 = 43 +43+43+43+43+43

Count bys: 43,86,129,172, 215, 258

Make an easier problem: (43x5) + 43x1= 215+ 43= 258

Base Ten

(40x6) + (3x6) = 240+18= 258

Expanded notation

27X34= (20+7) (30+ 4) FOIL this (FOIL= multiply first, outside, inside, last)

600+80+210+28=

Partial Products 27

x34

28

80

210

600

Total= 918

My division notes are not as sweet and neat, so if someone wants to add those...