Light travels in a straight line unless something prevents it from doing so, for example, reflection or scattering, and this can explain the formation of shadows


Light does appear to travel in straight lines
Light can differ in intensity and wavelength
The distinction between reflection and scattering, How images are formed in a mirror
The colour of an object depends on the wavelength of light that it scatters
Objects are seen when light enters the eye through the pupil
Self assessment