Introduction to Chemical Changes

During this lesson students were organized into groups. Each group had a
worksheet labeled physical and chemical changes. Each group had several
items which they were to examine for physical properties.
Students were instructed to put on safety glasses & rubber gloves.
Two students from each gathered trays of objects to examine.
Each tray included: a dirty penny, a small container with lemon juice,
a cup with a small amount of salt, a small plant, a rusty object,
and a dropper filled with vinegar & a cup with a tablespoon of baking soda.
Each group made a list of the physical characteristics of the objects.
Then the students were instructed to mix the baking soda and vinegar,
and take notes on the changes. Then they were asked to
drop the dirty penny in the container of lemon juice and salt,
and shake for several minutes, then remove the penny from
the container and note any changes. Students discussed the
differences in the changes that took place with the vinegar & baking soda,
and the change in the penny. I indicated that these were chemical changes
because a new substance was formed. We discussed the changes
that take place during photosynthesis as well as the
exchange of oxygen and carbon dioxide as we breathe.
We also discussed the changes that occur when an object rusts.
Students labeled the chemical changes
and then made a flow chart for each chemical change.