It's an approachable summary, and mostly well worded and accurate. I think that your explanation for the band gap adequately demonstrates why different materials have different conductivities, but doesn't really give a picture of why they have varying conductivity with temperature. To be fair, this is a much more complicated topic and depends upon your system to some extent. I personally would add to the discussion that there are two primary contributors to conductivity: the *number* of free electrons in the conduction band and how easily those electrons can move - essentially how much friction they experience. Both of these depend on temperature, but they have very different behaviours as a function of temperature. In semiconductors, you can effectively add free electrons (at room T) by doping and thus control the conductivity as you wish. But perhaps this discussion is too advanced for your audience, I think it's your call.

Other comments:

"The forces of other atoms also broadens the energy levels into wider bands of possible energies." reword this, maybe "bringing atoms close together causes their energy levels to broaden into wider bands".

"across the solid, electrons in the conductance band can flow" typo for "conduction".

"In insulators (substances with low conductivity), the band gap is wide, and few electrons will enter the conduction band." (but if you put enough energy in, basically any solid can conduct... very briefly!)

Otherwise great.

~Stooveth