Here you will see students as young as 4 and 5 years old doing algebra and "advanced" math, without ever knowing it's supposed to be hard.
You are invited to learn how to use this method...

Tuesday, December 15, 2009

Cross Multiplication


Building on that short foundation:

Remember, I am condensing hours and hours into less than 20 minutes. If you miss something or you don't "get it" watch them a couple times...

Two vids on Cross Multiplication. More explanation with words and maybe some pictures coming your way soon. Meantime go to Crewton Ramones's House of Math for more.

Also if you think this is cool, wait till you see the vids I make on algebra: problems like (x+1)(x+2) = x2+2x+2, I use exactly the same blocks.

More beginner multiplication at CRHOM.


  1. Nice representation work, but why call it cross multiplication? That's bound to be confused with cross multiplying, one of the the most poorly understood algorithms ever.

    Partial products would be a more common name for it.

    But, nice visuals!

  2. Actually when you get right down to it, it's the distributive theory of multiplication...wait till you see the algebra I'm eventually going to post. Using the same blocks problems like (x+1)(x+2)= x^2+3x+2 is also a snap...

  3. Love it! As soon as I saw your set-up it brought to mind distributive property and multiplying & factoring polynomials. If all elementary teachers taught multiplication & division this way, the jobs of middle & high school teachers would be soooo much easier!
    --Mrs. Fuller