The reason this is misleading is that if the light wave is not exactly vertical and not exactly horizontal, then some of the light will still get through the polarizing filter. We would say that the part or component of the light that is vertical would make it through the filter. You can see why this wouldn't work for boards and picket fences. Say you have two slides, one taken from each perspective, and light from one is plane polarized in one direction and light from the other one is plane polarized in the perpendicular direction. You shine these two slides at a screen, and when the light reflects off the screen it keeps its polarization.
White screens depolarize the light.
Explain that one side of the glasses lets through one polarization of light and the other side lets the other through. The circularly polarized components of plane polarized light When we imagine light waves, it is common to have a picture of plane polarized light in our heads. But this is only one of the ways in which we can visualize light. An alternative would be to think of the light wave as a sum of circularly polarized components. In order to understand this, we'll have to understand a little bit about vector addition.