Thursday, September 2, 2010
Chemical Changes: Gak
Create a solution of Borax in water. Pour a small amount of the solution in small cups (one for each student or pair of students).
Dilute some white glue with water, 1:1. Put a small amount of the diluted glue in small cups (one for each student or pair of students).
I use this as an introduction to chemical changes, so students don’t really have any background information.
Provide each student/pair of students with a cup of the Borax solution. They should document any observations they can make.
Provide each student/pair of students with a cup of glue. They should document any observations they can make.
Ask students to predict what will result if the contents of the two cups are combined.
Pour the Borax solution into the glue cup.
Stir the mixture using a stirring rod, popsicle stick, or straw.
After stirring, pour the excess water into the sink.
Knead the gak with your hands for several minutes until it is no longer sticky.
Document any observations that can be made about the putty.
Discuss the ways in which properties of the gak differ from those of the initial substances.
**Borax should be no where near student's mouth or eyes. Wear safety glasses and wash your hands thoroughly after doing this activity. If you can't trust your students not to drink the Borax solution, don't do this activity.