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 » numeracy

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

Topic: more about decimals
Replies: 4   Last Post: Dec 4, 2002 9:38 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Mark Schwartz

Posts: 48
Registered: 12/6/04
more about decimals
Posted: Nov 27, 2002 8:29 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Nancy and Martha gave me some things to think about and expand on; mainly,
the idea of number sense.

I don't teach algorithms either but rather I do try to get students engaged
in thinking about the relationships that underpin algorithms. For example,
I have them play with powers of ten in the place value system, moving left
or right in the system as they multiply or divide by powers of ten. It's a
playful thing and gets them thinking about certain relationships. They seem
to love the idea that any number to the zero power is 1. I don't drill on
it but I do then extend the ideas that evolve from multiply fractions to
the base-10 to see what happens to, as they say, "the number of zeroes down
there." This leads readily to the algorithm of moving the decimal point
around when multiplying. One class insisted that there should be a
comparable algorithm for division and we generated it but decided that it's
too cumbersome - as one student said "too many moving parts." They seem to
thrive on parsimony, particularly if they've been involved in the
generation of it.

thanks for the replies. Oh, about the "erroneous" multiplication of
decimals system that a student evolved ... I asked the student if I could
talk about it in class and he approved. I then discussed what I saw and
indicated that it was erroneous. I then asked if anyone would like to play
with it to come and show us how and why it's erroneous, or, would they
simply like me to show them. There are about 4 "teams" of students working
on it and will come back with their insights next week ... talk to me later
... mark

--- EarthLink: The #1 provider of the Real Internet.

-To unsubscribe from the Numeracy mail list send e-mail to
-In the body of the message type "unsubscribe numeracy your_address"

-If you have any questions e-mail

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.