Let's look at a few assessment scenarios. Try to determine what type of assessment is being used, formal or informal. 1  Example 1. 2  A kindergarten teacher sets aside the first 15 minutes of every day to allow students to explore, play or engage in any activity of their choice.
Chemical bonds are made or broken in order to create a new molecule. One example of a chemical reaction is the rusting of a steel garbage can. That rusting happens because the iron (Fe) in the metal combines with oxygen (O2) in the atmosphere. Chemical bonds are created and destroyed to finally make iron oxide (Fe2O3).
By Anne Marie Helmenstine, Ph.D. Definition: A chemical reaction is a chemical change which forms new substances. Also Known As: reaction, chemical change.Examples: The chemical reaction H 2 (g) + Â½ O 2 (g) â H 2 O(l) describes the formation of water from its elements.y Anne Marie Helmenstine, Ph.D. Definition: A chemical reaction is a chemical change which forms new substances. Also Known As: reaction, chemical change.