19. Ask learners to cover their eyes with their hands. Ask
them to describe what they can see. Typical responses
might include that
it is a bit dark or that they can see light coming in the
gaps. Explain that to make it completely dark we have to
block out all the light. Discuss the picture on page 40 of
the Learner’s Book. Talk about how there is often some
light in a bedroom at night –
from street lights or from light sources such as digital
alarm clocks or standby lights on electrical items.