Saturday, 10 March 2012

I'm already over the challenge thing

 Not surprising, but with contributions from a personal situation, I lost a lot of motivation. Plus two of my classes annoy me. But Year 7 continue to be lovely, so I will keep doing my best for them at least.

Year 7: We're going to be looking at prime and composite numbers and factors. The main activity I want to use for primes and composites is one from the Counting On numeracy framework. Students draw rectangles to find the factors of numbers (a different number on each sheet) then lay them on the floor (or stick to the wall) to create a bar graph of how many factors they have. Then you can instantly see prime numbers, and how one is not a prime, but has a special column all to itself. It also separates square numbers from other composites. After they've got the general idea I want to try an idea from Brent Vasicek at Scholastic for an in-class assessment of their understanding. I think I will give each child a number and then get them to sort themselves according to different criteria, e.g. primes over here, composites over there, sit down if you have 4 as a factor etc.


  1. Can you explain this activity in just a little more detail please - it sounds wonderful. Are you making the bar graph out of the rectangles? Or making a regular bar graph on top of the rectangle pictures? Also curious how it shows one is not prime (I thought this was just by definition - so it supports the Fundamental Theorem of Arithmetic).

    Keep up the blog - it's wonderful!

    1. Thanks! The original activity is in the Counting On activities document ( - page 159) and I made up a sort of set of worksheets to support that. So each worksheet represents a number, and on the sheet you use rectangles to figure out how many factors the number has, then you make a graph out of all the worksheets. The horizontal axis is the number of factors the number has. The vertical axis becomes frequency based on how many worksheets get put in that column. I took a picture, I'll upload it when I get home!

      As for one, I find a lot of students still think it is a prime, I guess because they can see it is not composite and they figure it fits the definition of "can only be divided by one and itself" which is often what they know. This way you can see all the primes in the "two factors" column, all the composites in the columns of more factors, and one by itself in the "one factor" column. It provides a visualisation of the idea I suppose.