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Grade 12 Maintaining Water Systems Task: Administration and Scoring Materials

This page provides the directions and questions as they were presented to students who took the Maintaining Water Systems task. In addition, following each question is a sample response, the scoring criteria used to judge performance on the question, and performance data for students in the nation.

In this task, students make a preliminary recommendation for which of two locations would be the better site for building a new town based on which location might have better water quality. Students then test samples of water from both locations and determine whether the samples meet federal standards for various pollutants. Finally, students provide a final recommendation for the better site to build the town based on the results.

See the test booklet.

Directions and Materials

Part 1

Part 2

Part 3

PART 3

The new town will be built with a water treatment plant to reduce or remove the pollutants at the site you choose (Town Site A or Town Site B). Diagram 4 below shows some major steps in a water treatment process. This process is similar to the one that will be used in the water treatment plant at the new town site.

Diagram 4

Image of a diagram showing the following process: Incoming water to be treated is sent to a Settling Tank where the water is allowed to stand (sedimentation). The water is then treated with chemicals (neutralization, oxidation-reduction, precipitation, and other chemical treatments). Next solid particles and organic matter are removed (filtration, biodegradation). The water is then disinfected (chlorination, irradiation). The water is next sprayed through fountains to remove volatile organic compounds (aeration), resulting in outgoing, treated drinking water.

Question 4

Table 2 below lists the major steps used in the water treatment process.

Use information from Tables 1A and 1B and your knowledge of physical, chemical, and biological processes to identify the pollutant(s) that could be removed or reduced in each treatment process step.

Enter in the last column of the table the water samples (S_A, S_B, or Both) where each pollutant you identified exceeds water quality standards.

Sample correct student response:

The table below is a transcription of a student response for question 4

Table 2: Water Treatment Processes

Water Treatment Process Step	Pollutant(s) That Could be Removed or Reduced in This Step	Site Where Pollutant Exceeds Standards (S_A, S_B, or Both)
Allow Water to Stand in a Settling Tank (Sedimentation)	Turbidity	S_B
Treat Water with Chemicals (Neutralization, Oxidation-Reduction, Precipitation, Other)	Nitrate Iron	S_B S_A
Remove Solid Particles and Organic Matter (Filtration, Biodegradation)	Turbidity	S_B
Disinfect Water (Chlorination, Irradiation)	Coliform	S_A
Spray Water Through Fountains to Remove Volatile Organic Compounds (Aeration)	Coliform	S_A

Question 4: Scoring Guide

This item was scored in 5 parts:

Part A: Sedimentation
Part B: Neutralization/Oxidation-Reduction/Precipitation/Other
Part C: Filtration/Biodegradation
Part D: Chlorination/Irradiation
Part E: Aeration

Part A

Complete:
Student response consists of two parts shown in Table 2: Row 1 (Sedimentation), Columns 2 and 3.

Indicates in Column 2 at least one of the correct pollutants turbidity (e.g., eroded soil particles, animal waste) that could be removed or reduced by allowing the water to stand in a settling tank, and no incorrect pollutants.
Indicates in Column 3 any site for which the listed pollutant exceeds standards according to the student’s response in Tables 1A and1B.

Blank in Column 3 is taken as “none”, and is credited if the pollutant is indicated in both Table 1A and Table 1B as not exceeding the maximum allowed levels.

Partial:
Student response is correct for Column 2 or Column 3.

Unsatisfactory/Incorrect:

Student response is inadequate or incorrect.

Part B

Complete:

Indicates in Column 2 at least one of the correct pollutants nitrate, pH, chloride, iron, copper, lead, or mercury that could be removed or reduced by treating the water with chemicals, and no incorrect pollutants.

Indicates in Column 3 any site where the listed pollutant exceeds standards according to the student’s response in Tables 1A and1B.

Blank in Column 3 is taken as “none”, and is credited if the pollutant is indicated in both Table 1A and Table 1B as not exceeding the maximum allowed levels.

Partial:
Student response is correct for Column 2 or Column 3.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Part C

Complete:
Student response consists of two parts shown in Table 2: Row 3 (Filtration/Biodegradation), Columns 2 and 3.

Indicates in Column 2 at least one of the correct pollutants total coliform or turbidity that could be removed or reduced by filtration/biodegradation, and no incorrect pollutants.
Indicates in Column 3 any site for which the listed pollutant exceeds standards according to the student’s response in Tables 1A and1B.

Blank in Column 3 is taken as “none”, and is credited if the pollutant is indicated in both Table 1A and Table 1B as not exceeding the maximum allowed levels.

Partial:
Student response is correct for Column 2 or Column 3.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Part D: Chlorination/Irradiation

Complete:
Student response consists of two parts shown in Table 2: Row 4 (Chlorination/Irradiation), Columns 2 and 3.

Indicates in Column 2 the correct pollutant total coliform that could be removed or reduced by disinfecting the water, and no incorrect pollutants.
Indicates in Column 3 any site for which the listed pollutant exceeds standards according to the student’s response in Tables 1A and1B.

Blank in Column 3 is taken as “none”, and is credited if the pollutant is indicated in both Table 1A and Table 1B as not exceeding the maximum allowed levels.

Partial:
Student response is correct for Column 2 or Column 3.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Part E

Complete:
Student response consists of two parts shown in Table 2: Row 5 (Aeration), Columns 2 and 3.

Indicates in Column 2 the correct pollutant benzene that could be removed or reduced by aerating the water, and no incorrect pollutants.
Indicates in Column 3 any site for which the listed pollutant exceeds the standards according to the student’s response in Tables 1A and1B.

Blank in Column 3 is taken as “none”, and is credited if the pollutant is indicated in both Table 1A and Table 1B as not exceeding the maximum allowed levels.

Partial:
Student response is correct for Column 2 or Column 3.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Composite Score:

Student response received one of five possible composite scores (Complete, Satisfactory, Essential, Partial, Unsatisfactory/Incorrect) based on the student's combined performance on Parts A, B, C, D, and E of the item. For example, a student response Complete for Part A, Complete for Part B, Complete for Part C, Complete for Part D, and Partial for Part E received a composite score of Satisfactory.

Composite Score	Score for Parts A, B, C, D, E
Complete	Complete for all 5 parts
Complete	Complete for 4 parts and Partial for 1 part
Satisfactory	Complete for 4 parts and Unsatisfactory/Incorrect for 1 part
	Complete for 3 parts and Partial for 2 parts
	Complete for 3 parts, Partial for 1 part, and Unsatisfactory/Incorrect for 1 part
	Complete for 2 parts and Partial for 3 parts
Essential	Complete for 3 parts and Unsatisfactory/Incorrect for 2 parts
	Complete for 2 parts, Partial for 2 parts, and Unsatisfactory/Incorrect for 1 part
	Complete for 1 part and Partial for 4 parts
	Complete for 1 part, Partial for 3 parts, and Unsatisfactory/Incorrect for 1 part
	Partial for 5 parts
	Complete for 2 parts and Unsatisfactory/Incorrect for 3 parts
	Complete for 1 part, Partial for 2 parts, and Unsatisfactory/Incorrect for 2 parts
	Partial for 4 parts, and Unsatisfactory/Incorrect for 1 part
Partial	Complete for 1 part, Partial for 1 part, and Unsatisfactory/Incorrect for 3 parts
	Partial for 3 parts and Unsatisfactory/Incorrect for 2 parts
	Complete for 1 part and Unsatisfactory/Incorrect for 4 parts
	Partial for 2 parts and Unsatisfactory/Incorrect for 3 parts
	Partial for 1 part and Unsatisfactory/Incorrect for 4 parts
Unsatisfactory/Incorrect	Unsatisfactory/Incorrect for 5 parts

Percentage of twelfth-grade students in each response category: 2009
Complete	Satisfactory	Essential	Partial	Unsatisfactory/ incorrect	Omitted
2	8	30	31	13	16
NOTE: Detail may not sum to totals because of rounding.

Question 5

Which of the potential town sites is a better location for building a new town?

A. Town Site A
B. Town Site B
C. Either Town Site A or Town Site B (neither site would be better than the other)

Support your choice using information from Table 1A, Table 1B, and Table 2.

Sample correct student response:

According to the information gathered, the pH level in Sample A was not drinkable and the total coliform level was too high. When I tested Sample B, the nitrate and turbidity level exceeded the maximum level. But after reading the treatment process, each individual step will filter, fix, and neutralize all these problems; therefore, Sample A or Sample B would be a good water source.

Question 5: Scoring Guide

Complete:
Student response selects (A) Town Site A, (B) Town Site B, or (C) Either Town Site A or Town Site B. Response justifies the selection by discussing the level of at least one specific pollutant at one site or both sites (required for (C) selection) consistent with student’s results in Tables 1A and/or 1B. Response also addresses at least one specific pollutant that would be treated in a water treatment plan, and this pollutant appears in student’s Table 2 in one of the water treatment process steps.

Partial:
Student response selects (A) Town Site A, ( B) Town Site B, or (C) Either Town Site A or Town Site B. Response justifies the selection by discussing the level of at least one specific pollutant at one site or both sites (required for (C) selection) consistent with student’s results in Tables 1A and/or 1B. Response does not discuss treating any specific pollutant, or discussion is inconsistent with Tables 1A and/or 1B.

Student response selects (A) Town Site A, (B) Town Site B, or (C) Either Town Site A or Town Site B. Response does not justify the selection, but addresses at least one specific pollutant that would be treated in a water treatment plan, and this pollutant appears in student’s Table 2 in one of the water treatment process steps.

Student response selects (A) Town Site A, (B) Town Site B, or (C) Either Town Site A or Town Site B. Response justifies the selection by comparing the levels of pollutants at both sites without mentioning specific pollutants. Response is evaluated based on comparing the pollutants exceeding maximum allowed levels consistent with student’s results in Table 1A and Table 1B, and/or comparing the pollutants for which treatment is needed at the two sites consistent with student’s results in Table 1A, Table 1B, and Table 2.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Percentage of twelfth-grade students in each response category: 2009
Complete	Partial	Unsatisfactory/ incorrect	Omitted
11	50	39	#
# Rounds to zero. NOTE: NOTE: Detail may not sum to totals because of rounding.

Question 6

Describe specific physical, chemical, and biological processes you would need to use in the water treatment plant at the site(s) you chose. Refer to Table 2 in your answer.

Sample correct student response:

The water would need to be treated with chemicals in order to make the water neutral rather than acidic. Also, the water would need to be disinfected because it has a high level of e-coli due to the fact it is downstream from animal waste. It may be beneficial to also treat the water for iron because the level of iron was high.

Question 6: Scoring Guide

Student response identifies one or more pollutants and provides a valid description of one or more of the steps that are needed to remove the pollutant. The pollutant and the step need to match with each other to receive full credit.

For example, allowing water to stand in a settling tank (Sedimentation) is a (physical) process that allows heavy particles (turbidity) to settle to the bottom of the settling tank. Disinfecting water (Chlorination) is a (chemical) process that kills potentially harmful microorganisms (total coliforms) in the water.

Partial:

Student response identifies one or more pollutants and provides an incomplete description of one or more of the processes that are needed to remove the pollutant(s). Response may paraphrase the information in Column 1 of Table 2.

Unsatisfactory/Incorrect:
Student response is inadequate or incorrect.

Percentage of twelfth-grade students in each response category: 2009
Complete	Partial	Unsatisfactory/ incorrect	Omitted
6	20	71	#
# Rounds to zero. NOTE: Detail may not sum to totals because of rounding.

SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Science Assessment.