Students will mix ingredients to create a chemical change and "Blobber" - a substance similar to silly putty.
White glue is made up of millions of polymers. When polymers are dissolved like they are in glue they slide around each other letting the glue flow. However, they are so long, that when they flow they get in each others way making the glue more viscous. Viscous means that glue flows more slowly than water. When you add a borax solution to the glue the polymers change. The borax makes them cross link or connect to each other like a net. The more tangled the polymers get the more water they trap creating a jelly like feel. Tangled molecules change and are even more difficult to pour. This makes the solution even more viscous than glue. The change that takes place to the polymers by adding the borax solution is a chemical change.
Indicators of a chemical change can be color, a new odor, light or change in heat is given off. When making Blobber two liquids are mixed together forming a precipitate. A precipitate is also an indication that a chemical change has taken place.
Super Science Concoctions, by Jill Frankel Hauser talks about a mistake that paid off, "Try as he might, the chemist James Wright was never able to create rubber in the laboratory. But one of the mistakes did become a very popular toy. When he added boric acid to silicone oil he created a bouncing solid that oozed like a liquid. You probably know it as Silly Putty!" (pg. 152).
2. Manifest Scientific Attitudes and Interests.
Invitation to Learn
What happens when you mix glue, and a mixture of borax and water together? Can you bend it, bounce it, even blow it up like a balloon. Why is it so moldable and flexible?
Corcoran, Carol A.; (May-Jun 2004). A teacher's guide to alternative assessment: Taking the first steps. Clearing house, Volume 77.5, p.213.
Moon, Tonya R., Brighton, Catherine M., Callahan, Carolyn M., & Robinson, Ann; (Winter/Spring 2005). Development of authentic assessments for the middle school classroom journal of secondary gifted education, Volume 16.2/3, pp. 119-133, 15p
DeGeorge, Barbara; Santoro, Anne Marie C.C. (Nov-Dec 2004). Manipulative: A hands-on approach to math. Principal volume 84 n2 pp.28-28 (Ej693871). January 31, 2006 from http://www.eric.ed.gov
Renwick, Lucille C.C. (Jan-Feb 2004). Hands-on learning. Instructor Vol. 113.5 p.9-9, 1/2p, 1c (12403496). January 31, 2006 from http://www.eric.ed.gov
Hands-on learning is critical to students' understanding of science concepts. Research shows that hands-on projects actually help children learn better. Hands-on learning helps students more readily understand concepts and boosts their self-confidence.
Performance Assessment is the collection and evaluation of evidence of student learning, focusing on indicators of meaningful and valuable student progress. This type of assessment asks students to perform, create, produce or do something. It tapes into higher-level thinking and problem-solving skills. It uses tasks that represent meaningful instructional activities involving real world applications and using human judgment to do the scoring.