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Chemical Changes
Administration Procedures
8th Grade Performance Task
Contributed by: New York State Education Department (NYSED)
NYS Alternative Assessment in Science Project (1996)


Students observe two types of interactions in a sealed plastic bag. One bag contains baking soda and water, and the other baking soda and vinegar. Students will determine what evidence indicates that a chemical change is occurring.

This task assesses students' abilities to make simple observations, develop descriptions and explanations of phenomena, and apply that understanding to an additional hypothetical situation.

This task is designed to take students approximately 10-15 minutes to complete.

Overall Task Content Area:

Earth Science


Specific Knowledge Areas:

Properties and changes of properties in matter

Performance Expectations:

  • conducting investigations
  • gathering data
  • formulating conclusions from investigational data
  • applying scientific principles to develop explanations and solve new problems

National Science Education Standards:

8 B PS 1: Properties and changes of properties in matter - Grades 5-8
1.2 Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved. Substances often are placed in categories or groups if they react in similar ways; metals is an example of such a group.

8 A SI 1: Abilities necessary to do scientific inquiry - Grades 5-8
1.4 Develop descriptions, explanations, predictions, and models using evidence. Students should base their explanation on what they observed, and as they develop cognitive skills, they should be able to differentiate explanation from description providing causes for effects and establishing relationships based on evidence and logical argument. This standards requires a subject knowledge base so the students can effectively conduct investigations, because developing explanations establishes connections between the content of science and the contexts within which students develop new knowledge.

1.8 Use mathematics in all aspects of scientific inquiry. Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions; to gather, organize, and present data; and to structure convincing explanations.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National Council of Teachers of Mathematics:

Algebra (AL1): Understand patterns, relations and functions.

Problem Solving (PS2): Solve problems that arise in mathematics and in other contexts.

General Instructions to the Teacher:

This task is designed to take students approximately 10-15 minutes to complete.

Students may work individually or with groups during this exercise.

Students should be ready to work as soon as the period begins. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for "Chemical Changes":

The teacher will need:

  • 1 lb box of baking soda
  • 1 quart of white vinegar
  • small cups or containers

At this station students should have:

  • 2 resealable bags labeled A and B
  • 2 twist ties
  • 1 plastic teaspoon
  • 50 ml graduated cylinder
  • baking soda
  • white vinegar
  • water
  • paper towels
  • safety goggles

Advance Preparation:

  • A 1 pound box of baking soda and one (1) quart of vinegar is sufficient for a class of approximately thirty (30) students.
  • A supply of baking soda and vinegar in small labeled containers must be placed at each student station.
  • The resealable bags may be washed and reused.
  • Use a 'good' brand of vinegar. Not all vinegars have the same acid content.


  • Check MSDS (Materials Safety Data Chart) for further laboratory precautions.
  • Laboratory safety procedure is required.
  • Safety goggles must be worn during this experiment.
  • Be aware that the baking soda and vinegar bag will expand greatly due to the carbon dioxide production.
  • Be careful.
  • Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.




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