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Massachusetts Comprehensive Assessment System

2014, Grade 8 Science and Technology/Engineering

  Question 10: Open-Response  
A group of students do an activity with baking soda and vinegar. The steps of the activity are listed below.
  1. Pour 100 g of vinegar into a flask.
  2. Measure the temperature of the vinegar.
  3. Add 10 g of baking soda to the flask.
  4. Observe as the contents of the flask fizz (produce bubbles).
  5. Measure the temperature of the contents of the flask and observe any change in temperature.
  1. Describe one piece of evidence that a chemical reaction occurs when baking soda is added to vinegar.
  2. What should be the total mass of all the products of the reaction? Show your calculations or explain your answer, and include units in your answer.
After the fizzing stops, the students determine that the liquid in the flask has a mass of 105 g.
  1. Describe how to change the activity to show that the total mass of all the products is the value you calculated in part (b). Explain your reasoning.

Scoring Guide and Sample Student Work
Select a score point in the table below to view the sample student response.

ScoreDescription
4 The response demonstrates a thorough understanding of chemical reactions and how mass is conserved in a closed system. The response clearly describes evidence of a chemical reaction. The response correctly determines the total mass of all the products of the reaction and includes calculations or an explanation. The response also clearly describes how to change the activity to show conservation of mass and explains the reasoning.
4
3 The response demonstrates a general understanding of chemical reactions and how mass is conserved in a closed system.
2 The response demonstrates a limited understanding of chemical reactions and how mass is conserved in a closed system.
1 The response demonstrates a minimal understanding of chemical reactions and how mass is conserved in a closed system.
0 The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

Grade 8 Science and Technology/Engineering

Question 9: Life Science
Question 10: Physical Sciences

Return to the MCAS 2014 Student Work Directory



Last Updated: November 16, 2017
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