administration student task rubric student work technical quality
Water-Holding Capacity

Grade 9-12 Performance Task
Developed by: New York State Education Department (NYSED)
University of Buffalo and NORC (1991)

Task-Specific Scoring Criteria for Biology Task #6: Water Holding Capacity


1. Statement of hypothesis  
- Effect linked to variable Water holding capacity increases with decreasing density of soil, so that capacity of peat moss > soil > sand.
- Directionality of effect The lighter the soil, the greater its water holding capacity.
- Expected effect/change The water holding capacity of sand, soil, and moss varies.
- Independent variable Soil texture (sand, soil, moss) or size of particles.
- Dependent variable Water holding capacity (retention of water).
2. Procedures for investigation  
- Detailed procedure/experimentally feasible Same quantity of water and soil are used for each soil sample and comparison is made on water retained, not collected.
- Sequence to plan Steps are presented adequately with sufficient detail (i.e. time, 10 minutes; quantities of soil; water; give directions to fix the funnels).
- General strategy Suggests method to compare drainage of three soils.
- Safety procedures *
- Use of equipment/diagram Appropriate use of equipment and materials suggested, such as use of beaker, graduated cylinder, funnel, soils
3. Plan for recording and organizing observations/data  
- Space for manipulation of data or qualitative description Space is provided adequately for manipulation of data.
- Matched to plan Plan is matched to procedure outlined in step 2 above.
- Organized sequentially Record relevant data sequentially in a table.
- Labelled fully (units included) Time in minutes or seconds, volume in mL.
- Variables identified Water holding capacity, soil texture, time



4. Quality of observations/data  
- Consistent data Amount of water collected; sand > soil > moss
- Accurate measurements, observations Each soil is observed for ten minutes and volume measured to nearest mL.
- Completed data table Time and volumes for three soils are recorded.
- Correct units Water volumes are recorded as mL
- Qualitative description *
5. Graph Not required for this task.
- Curve is appropriate to data trend  
- Points plotted accurately  
- Appropriate scale  
- Axes labelled with variabls  
- Variables placed on correct axes  
6. Calculations Not required for this task.
- Calculated accurately  
- Substituted correctly into relationship  
- Relationship stated or implied  
- Units used correctly  
- Use all data available  
7. Conclusion  
- Consistent with scientific principle Water holding capacity increases with decreasing density of soil, so that capacity of moss is greatest, then soil, then sand.
- Sources of error *
- Consistent with data Conclusion stated is consistent with the student's data (1)
- Relationship among variables stated Relationship between water holding capacity and soil texture is clear. Conclusion is based on volume of water retained, not volume collected. (1)
- Variables stated in conclusion Water holding capacity, soil texture (sand, soil, moss).


* These elements were not scored in this task; a "holistic" scoring approach was utilized so that the other four elements had a total value of 5 points.

(1) A point can be earned for each of these elements if the conclusion reflects results of student's experiment. No credit is lost here if conclusion deos not match scientific principle.


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