Friday, 11 October 2013

This year's Forest of Factors

Following on from last year's post Important Factors, and after our work finding prime numbers with Cuisenaire rods and in the playground, Year 4 had a go at making prime factor trees this year. Here's our Forest of Factors:

See more on the Year 4 blog
Our trees made a really big Forest of Factors display for the primary corridor. As the Year 2 and Year 3 children are passing it regularly, it was a good idea to explain the display to them. We did it without using the words "factor", "multiple" or "prime" so that it would be easier for them to understand:

 "Hello everyone. This is our Forest of Factors."

"1, 2, 3, 4.... 40"

"What do you notice about our pictures?"

"Number 1 is my bird. It's different to all the other numbers. If you times something by 1 it just stays the same number."

"So 1 is special, and we don't think about it with our trees and mushrooms. It's just flying up in the sky!"

"Some of the numbers are simple trees. Look at 38. 38 is 19 times 2, so we've given it two branches that finish with flowers."

"Ten is five times two."

"26 is 13 times 2."

"These ones had just two branches and two flowers."

"But some of the trees have more flowers. Like 12, and 32."

"With the mushrooms there's no two numbers that you can times together to make that number."

"Can you see a number that is a mushroom?"

"So that's our Forest of Factors. We hope you understand it a bit better now."

Wednesday, 2 October 2013

Finding prime numbers in Year 4

In Year 4 we've been looking at prime numbers this week.

Some of us have been out in the playground, using the hundred square there:

Here's a how we did it:

Later we had a go in the classroom, using a photo of the hundred square (16 colour bitmap format):

and, on Paint, filling he numbers in the 5, 3, 7 and 2 times table with colour:

And there we have it: the grey ones (except for 1) are the prime numbers!

(also blogged on the Year 4 blog)