  We describe a simple experiment for measuring the thermal expansion
coefficient of a metal wire and discuss how the experiment can be used as a
tool for exploring the interplay of measurement uncertainty and scientific
models. In particular, we probe the regimes of applicability of three models of
the wire: stiff and massless, elastic and massless, and elastic and massive.
Using both analytical and empirical techniques, we present the conditions under
which the wire's mass and elasticity can be neglected. By accounting for these
effects, we measure nichrome's thermal expansion coefficient to be 17.1(1.3)
ppm/K, which is consistent with the accepted value at the 8% level.
