Last printed 10/9/2001 10:21 PMPage 1 of 5
Chemistry Lab Write Up Guidelines
1)Follow Directions (FD): Follow the directions of the lab.
2)Calculations (C):
a)There should be a separate section for calculations with the title “Calculations”.
b)Model Equation (ME): Show the model equation for each calculation. For example:
Percent Error = Absolute Error * 100% or Density = Mass
Theoritical Value Volume
c)Show all the Work (SW): Show all math operations (what is added, subtracted, multiplied, or divided. DO NOT SHOW HOW they were added subtracted, multiplied, or divided.
d)Unit (U): Place a unit with each number. A number without a unit is meaningless.
e)Transfer (T): make sure that the exact value in the data table is transferred to the calculation section.
f)Cross Reference (CR): Data used in calculations should be cross-referenced to the data table using the row letter and column number.
3)Data Tables (DT)
a)Accuracy (A): Always read instruments to their correct precision (to the smallest markings).
i)To find the precision of an instrument, divide the difference between the printed values by the number of spaces between them.
2 3
| |
|___|___|___|___|___|
^
ii)Write all the digits, including zeros, to that place. If the last digit is 0 then use 0. For example, reading the ^ on the scale above, it would be recorded as 2.8 in a data table. If the ^ had been under the 3 it should be recorded as 3.0 in the data table.
b)Missing Data (MD): These should be a place in the data table every time the procedure asks the student to record data. There should be a place in the data table for the answer to every calculation in the calculation section.
c)Data Reference (DR): The top row should have a number for each box, and the left column should have a letter for each box. When these are combined together it is possible to make a data reference for each piece of data in the table.
d)Sloppy (S): The data table should be constructed in a neat, easy to read, manner.
4)Conclusion: (Use ACE Strategy and the Maryland Science Rubric)
a)Restate the question (RS): Restate the question in the answer.
b)Proper English (ENG): Use proper grammar and complete sentences.
i)Complete Sentences (CS): Answers should be written in complete sentences.
ii)Abbreviations (AB): Do not use abbreviations. Spell out number ten or less (unless referring to data from the data table).
iii)Spelling (SP): Correctly spell words (this is a formal writing).
iv)Third Person (3rd):
c)Evidence (E): Cite evidence from the data tables to support the conclusion. Students may also cite information from textbooks or other authorities. Give credit to the sources of information (use in-text citations).
i)Cross Reference (CR): When referring to data in the data table give the corresponding cross-reference.
d)Terminology (TM ): Students should use scientific language to describe scientific processes.
e)Full Explanation (FE): Fully explain the answer.
f)Sloppy (S): The paper should be neat and easy to read when turned in.
g)Wrong Answer (AN): The answer was wrong or incomplete
h)Application (AP): Apply the answer to a real-life situation or a practical problem.
Grading Symbols
Calculations/Data Table
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
A =Accuracy
C =Calculations
CR =Cross Reference
DR =Data Reference
DT = Data Table Error
FD =Follow Directions
MD =Missing Data/Incomplete Data
ME = Model Equation
S =Sloppy
SW =Show Work
T =Transfer Error
U =Units
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
Conclusion
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
3rd =Use Third Person
AB =No Abbreviations
AN =Wrong answer.
AP =Poor/Missing Application
CR =Use Cross References
CS =Use complete sentences.
E =Use evidence to support answer.
ENG:Use proper English.
FD = Follow directions.
FE:Full explanation of answer.
S =Sloppy paper.
RS =Restate answer.
TM =Use scientific terminology.
SP =Use proper spelling.
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
Graph
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
Scale should be larger
О =Point not enclosed (circled).
DT =Data table of ordered pairs is missing/incorrect.
FD =Follow directions.
IN =Each box on an axis should have the same incremental value.
L =Legend is missing or incorrect.
LA =Label for axis is missing/incorrect.
P =Points were not properly plotted.
TI =Title of graph is missing/incorrect.
S = Scale is incorrect/missing.
U = Unit is incorrect/missing.
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc2001 Tim Bass
Last printed 10/9/2001 10:21 PMPage 1 of 5
Chemistry: Lab Grades
- Each activity, and each section of the activity, is assigned certain numbers of points. No matter how bad a section is, only points that are possible can be deducted from each part (no negative scores).
- A Rubric (scoring guide) is made for each lab.
- To get the activity grade divide the points made by the points possible and multiply by 100.
Graphing (See also Pg 800-804)
Grading Criteria:
1)Title at the top of the page.
a)Dependent versus the Independent Variable
2)Graph Scale
a)Should be as large as possible. (See Determine Scale)
i)Should not use 2 sheets of graph paper.
ii)Should cover more than half of the graph paper in both (x & y) directions.
b)Should have equal divisions.
c)Should be easy to read, not more than one digit in the scale unless 0.25 is used. Students may use 1, 2, 3, 4, or 5 as digits.
3)Data Points
a)Independent Variable: Determined (chosen) by the experimenter.
i)Should be plotted on the x axis.
b)Dependent Variable: Varies according the independent variable.
i)Should be plotted on the y axis.
c)Should be accurately plotted on the graph at the proper coordinates for the ordered pair.
d)Each data point should be enclosed (circled.) to easily find it.
4)Different Axis (Both x and y)
a)Should have a descriptive label.
b)Should show the scale. Students may use = .5 Epochs as an example.
c)Must show the units in parenthesis (Epochs).
5)Legend
a)If more than one line or set of data is plotted on the graph a legend is required.
6)Neatness
Determine The Scale
1)Determine the number of available boxes.
a)Count the boxes on the axis.
b)Subtract enough boxes to give adequate room for the axis labels and graph title. 32 Total # Boxes in y axis. 32 - 3 = 29 Available
2)Determine the range.
a)Range: Difference between the largest and smallest value plotted on an axis.
b)100 – 0 = 100 (Range).
3)Divide the range by available boxes.
a)100/29 = 3.448
4)Round the number up to one digit, either a 1,2, or 5. 3.448 5 Scale is: = 5 %
a)0.03293 0.05
b)29,343 50,000
Interpret the Graph
1)Straight Line: If the data points lie roughly along a straight line, the variable have either a linear relationship or are directly proportional.
a)Linear Relationship: the line has the general formula y = x + b. Each y value increases by a constant amount.
b)Directly Proportional: the line has the general formula y=mx + b where m is the slope of the line and b is the y intercept and is a constant. Each value of y is a multiple of the value x.
2)Curved Line: If the data points lie along a curve that drops from right to left (like the example to the left) then the quantities have an inverse relationship.
a)Inversely Proportional: the line has the general formula y = 1/mx + b. As one variable increases the other variable decreases.
b)It is difficult to interpret and determine the equation for an inversely proportional graph. To determine the equation convert the x axis data to a directly proportional relationship by using the reciprocal of the data. If it is an inversely proportional graph it will produce a directly proportional graph where the slope of the line can be easily calculated.
3)What does the line mean? Most of the time in chemistry the line expresses some property of the substance being graphed. For example, if one graphed volume vs. mass the resulting slope of the line would represent the density of the substance.
4)Reading the graph:
a)If the graph is properly constructed is should be able to read both within the data points and outside the data points plotted (the scale of the graph may have to be adjusted to do this).
i)Interpolation: To read points on the line within the range of the points plotted.
ii)Extrapolation: To extend a line and read points on the extended line outside the range of the points plotted.
Types of Graphs
1)Single Set of Data
a)Line Graph
2)Multiple Sets of Data
a)Overlay Graphs: Simply plotting more than one set of data on the same graph.
b)Cumulative Graphs: Plotting multiple lines by adding one axis (usually the y axis) of a line to all previous lines plotted.
i)Types of Cumulative Graphs
(1)Line Graph:
(2)Bar Graph
(3)Pie Graph: All pie graphs are cumulative by nature.
Determining the Appropriate Type of Graph (to use with the data).
1)Depends on the purpose of the graph. Answer the following questions:
a)Does the slope of the line need to be determined?
b)How is the graph to be read?
c)Does the data being presented need to be compared?
d)Why is the graph being built?
C:\My Files 3\School\Chemistry\Opening\Chemistry Lab Guidelines.doc 2001 Tim Bass