Wednesday, 11 February 2015

Multiplication and Division

The very important concept of Multiplication and Division is being introduced in class currently.  The Grade 3 Manitoba Math curriculum indicates that students should know their facts to 5 X 5 by June of Grade 3.  Knowing the facts is only a small part of the expectations, they need to understand what it means to multiply and divide.

When I introduce multiplying, I have them refer to 4 ways to think about it so that they understand what it really means.
1. Circles and Stars - Draw it out in a picture.  For 3 X 4, make 3 circles and draw 4 stars in each one.  This shows the groups in picture form and we quickly find it is not that effiecient and mistakes can be made.
2. Repeated Addition - 3 X 5 can be shown as 5 + 5 + 5 and skip counting can help to get the answer too.
3. Number Line - Another way to demonstrate multiplication is using a number line and showing jumps.  4 X 2 can be shown with 4 jumps of 2, skip counting 2,4,6,8.  Quickly some kids notice that the numbers can be reversed and 2 jumps of 4 will give the same answer but quicker.
4. Arrays - drawing boxes or objects in equal rows helps students see multiplication in a concrete way.  3 X 3 can be drawn in a square 3 boxes high and 3 boxes long.
Having learned the multiplication first, then turning it around with division is where we are right now with the Grade 3's.  Does anyone remember the Animaniacs?  Check out this video!