Children readily understand how important sight is. Placing a blindfold on a child and having him navigate across a room can help emphasize this importance. Blindfolding a child can also teach lessons on how blind people can manage without sight. Have them guess what something is, like sandpaper or a toothbrush, while blindfolded; it will teach how important the sense of touch is. Letting them guess something by smelling or tasting it is another good lesson.
The sense of smell can be tested by putting various items in opaque containers and having the children sniff the contents --- blindfolded, of course. Food items like popcorn, onions, oranges and coffee are easily distinguished from one another. It is also fun to include household items with recognizable odors like baby powder or Play-Doh.
The sense of sound allows us to hear different volumes, tones and frequencies. Small children can learn this lesson by filling plastic opaque containers with various objects like paper clips, marbles and cotton balls. They should be able to distinguish whether something is big or small, heavy or light, based simply on what they hear.
The sense of smell is an important helper to the sense of taste. Small cubes of white vegetables and fruits, like apples, pears, turnips and potatoes, all appear similar but taste differently. Having students hold their noses shut while sampling each of these and trying to guess, based on taste, what they are is a good illustration of how strongly linked these two senses are.