Very very basic question about Mathematica expressions

*To*: mathgroup at smc.vnet.net*Subject*: [mg111090] Very very basic question about Mathematica expressions*From*: Sam Takoy <sam.takoy at yahoo.com>*Date*: Tue, 20 Jul 2010 03:42:13 -0400 (EDT)

Hi, I find that I don't understand a very basic thing about the building blocks of Mathematica. When the first command is s = x + h I figured that (string?) "s" represents (string?) "x+h". This theory pans out when one tries s^2 or D[s, x] or Integrate[s, {x, 0, h}] and s /. h -> 1 But then by doesn't this work: Manipulate[ Plot[s, {x, 0, h}], {h, 0.1, 1}] Many thanks in advance!