Age 10? Think you probably did. Atoms and electrons were not new to us when we entered secondary school. We didn’t know much about them, only their existence and what they “look” like in the classical nucleus/electron sort of way. We did have fairly science-happy primary school teachers though. 😐
samuri – not strictly correct but gives a functional representation a kid will understand. The actual answer, which I am led to believe has been understood for a few decades, is that the light interacts with the sub-atomic particles (electrons primarily) and depending on the energy of the wavelength of light impacting the substance and the possible energy states of the electrons in the material impacted, it will either be absorbed or allowed to pass through. None of the energy levels of visible light match the discrete energy levels of the electrons in glass’s structure, and so none are absorbed. Deep UV, on the other hand, is absorbed by glass as the energy levels coincide. As for the glass/silica point, that could be because glass and silica have differing crystal structures (slightly) (glass isn’t JUST sand) and as such differing electron energy levels are available to absorb the visible wavelengths? Add that to the fact that sand is a mass of interfaces – take glass and crush it to a powder and you’ll not see through that either because of the scattering effect of the surfaces and angles presented to the light.