BACKGROUND:

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 17^th 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 understand.

Early people probably started to realize that clear substances could increase an object’s 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

PROCEDURE:

1. 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.
     
2. 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.
      
3. 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.
     
4. 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.