The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » Education » math-teach

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: Research on "Twice as big"
Replies: 19   Last Post: Feb 27, 2011 1:15 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Jonathan J. Crabtree

Posts: 355
From: Melbourne Australia
Registered: 12/19/10
Research on "Twice as big"
Posted: Jan 20, 2011 7:05 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Do you agree with the idea the brain processes size by observed surface area?

This is why I ask.

I ask adults to draw a square. Then I ask them to draw a square "Twice as big" as the first.

Almost every time the second square is four times as big as the first.

It is rare that someone diagonally halves the square to create the new square out of the long side of the triangle created inside the original square.

We all learnt from school about square roots yet it seems that adult brains cannot draw simple shapes such as squares "Twice as big".

Is the problem because we all learnt shape from MAB where we are taught "Twice as big" means double?

Are children being confused when one square unit made "Twice as big" suddenly becomes a rectangle 2 unit long?

I understand that MAB is meant to teach place value.

However I wonder if it does so at the expense of proportion?

Would an 'untrained' child believe a root two times root two square is twice as big as a unit square? Or would that child, like an adult, believe a root four times root four square (2x2) is "Twice as big" as a unit square?

My apologies for asking such a simple question. All the childrens' books I have show pictures of half a circle or half a square and so on. I am yet to find a child's math book that retains original shapes when a circle or square is made "Twice as big".

I know there are lots of questions withing this post, yet any simple insights would be appreciated as would direction on any research.

Thank you,
Jonathan :)

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.