There are many things that we cannot see with our eyes, but that
doesn't mean they don't exist. Early humans did not know about
protozoa, bacteria or viruses, so it was very difficult for them to
know what happened to them when they got sick. The use of hand lenses
in the 17th century allowed scientists to begin
understanding what caused illness. Creating lenses was an art. Early
microscopes used an understanding of physics to make several
individual lenses to help see objects that humans cannot see with
their naked eye. The more we observe about our world, the more we can
Early people probably started to realize that clear substances
could increase an objectís image. As the science of glass making
matured, glass could be used to help magnify objects. The glass has to
be curved just right and be so thick in order to magnify
- Students can make their own
magnifying glass very easily. Twist a piece of wire around a pencil or
cylinder-shaped object to make a small loop. Remove the object so the
wire loop remains.
- Dip the loop into a glass of water.
When you take the wire out of the glass, a drop of water will stay in
the loop (due to surface tension). A little soap in a glass of water
will make the water film tougher. Make sure to keep the diameter of
the loop small.
- Carefully hold the loop over a piece
of newspaper. The letters, viewed through the water, look larger. You
just made a magnifying lens! Discuss how a magnifying lens can be made
of any material, as long as it enlarges an object.
- Continue discussing observation with your
students. Observation uses sight from eyes or the other senses of
touch, taste, feel, or hearing. Increasing the observational
powers of students requires exercises that assist a child observe
more closely. Have the students describe the classroom and see if
there are any objects that change from day to day. Discuss how
observation can also be done on their way to school. Ask students
to notice if the trees or flowers have changed color, if a new dog
is on a street, or if someone moved from a house. There are many
things happening in our lives, and we observe them as they are
happening. Recognizing and taking a mental note of our
surroundings helps encourage observational skills.