Q&A #2179

Teachers' Lounge Discussion: Algebraic expressions and equations

T2T || FAQ || Ask T2T || Teachers' Lounge || Browse || Search || T2T Associates || About T2T

View entire discussion
[<< prev] [ next >>]

From: Diane White

To: Teacher2Teacher Public Discussion
Date: 2002091818:46:52
Subject: Teaching algebraic expressions

The one thing that I found is that the wording in an expression is

I have taught pre-algebra for many years and can offer you this

1.  Explain the simple number statements first:  3+4; 5x6; 28/4, etc.

2.  Now substitue a variable for a value.  Example rather than
    3+4, we have x+4.

3.  Turn the standard form numbers into words for the simple math
    facts:  three plus four; five times six, etc.

4.  Now substitute the variable for the number in words:
    x plus 4; five times x; 28 divided by x or x divided by 7

5.  Give the students a list of the various words meaning 
    addition:  plus, sum of, increased by, more, more than - to
    cite just a few.  Follow this up with subtraction, multiplication
    and division terms.

6.  Have them become extremely familiar with all the key words.

7.  Now, teach them the difference between a math statement and
    an algebraic expression.  It is a simple matter of
    substituting a variable for a number.

8.  Be very careful to note the following:  When you use
    more than and less than you must explain to your students
    that the values here are transposed.
    Example:  5 more than a number is not 5+x but x+5.
    Example:  10 less than a number is not 10 - x but x - 10.
    This is the only case in all of pre-algebra that the students
    the value of proper placement of value and variable.

9.  When all is said and done, and your students cannot determine
    the difference between a constant value and a variable - do
    what I started many years ago.  
    I simply explain to my students that a constant value - one 
    which never changes - is my height.  It stays at 5'3".
    However, my weight is a variable - it changes all the time
    hourly as I get older!

Hope that this was informative - if not it was nice speaking to
you Teacher To Teacher.

Diane White

Post a reply to this message
Post a related public discussion message
Ask Teacher2Teacher a new question

[Privacy Policy] [Terms of Use]

Math Forum Home || The Math Library || Quick Reference || Math Forum Search

Teacher2Teacher - T2T ®
© 1994- The Math Forum at NCTM. All rights reserved.