PALS - Rubric

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

Task-Specific Scoring Criteria for Biology Task #4: Diffusion

PART A: EXPERIMENT DESIGN

1. Statement of hypothesis
- Effect linked to variable	As concentration and time increase, distance of diffusion also increases; cubes.
- Directionality of effect	Distance of diffusion increases.
- Expected effect/change	Distance of KMnO4 varies with concentration and/or time.
- Independent variable	Time, concentration
- Dependent variable	Distance of KMnO4 that travels into the cubes.
2. Procedures for investigation
- Detailed procedure/experimentally feasible	Plan includes measurement of diffusion distances from a combination of concentrations (1%, 5%, 10%) and time (e.g. 5m, 10m, 15m, 20m) that the cubes stay in the solution.
- Sequence to plan	At least two times and two concentrations are included in plan.
- General strategy	Plan includes varying time and concentration.
- Safety procedures	Care not to spill KMnO4; wearing apron and goggles; care in using scalpel might be suggested.
- Use of equipment/diagram	Appropriate equipment and materials are suggested.
3. Plan for recording and organizing observations/data
- Space for manipulation of data or qualitative description	* (Space for qualitative description might be included).
- Matched to plan	Plan includes observations and data which are consistent with the plan.
- Organized sequentially	Organized so that recording follows data as generated.
- Labelled fully (units included)	All columns and rows are identified, correct units of measurement are used.
- Variables identified	Time, concentration, and diffusion distance are clearly indicated.

* 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.

PART B: EXPERIMENT REPORT

4. Quality of observations/data
- Consistent data	Distance increases with increasing concentration and time.@
- Accurate measurements/observations	Accurate measurement of the distance reached by the diffusing KMnO4 in every five minutes.@
- Completed data table	All data entered in the table.
- Correct units	Distances are labelled as mm.
-Qualitative description	* (Variability of distance of diffusion within a single cube might be mentioned
5. Graph
- Curve is appropriate to data trend	Curve drawn best fits data points.
- Points plotted accurately	Plotted points are accurate.
- Appropriate scale	Values of scales are appropriate to ranges of data.
- Axes labelled with variables	Time in minutes; concentration in percentages; distance in mm.
- Variables placed on correct axes	Dependent variable, distance of diffusion is the y axis; independent variables, time and concentration (on the x axis) can be placed on separate graphs OR combined as three separate plots of concentration within one graph with time as the x axis
6. Calculations	Not required for this task
- Calculated correctly
- Substituted correctly into relationship
- Relationship stated or implied
- Units used correctly
- Use all data available
7. Conclusion
- Consistent with scientific principle	As concentration and time increase, distance of diffusion also increases.
- Sources of error	* (Measurement of distance may be hard to measure accurately.)
- Consistent with data	Consistent with student's experimental results. 1
- Relationship among variables stated	Distance of diffusion is related to concentration of KMnO4 and/or time. 1
- Variables stated in conclusion	Distance of diffusion, concentration of KMnO4 solution, time.