Guidelines for writing a lab report
Contents
1. Keeton et al 1993 35 Adding CO to water decreases the pH by forming carbonic acid Smith 1990 204 removing CO increases the pH Smith 1990 204 Purpose The purpose of this experiment was to determine if lowered pH 25 levels induce respiratory movements in stoneflies Further the experiment was an effective way to learn about pH how to measure pH with a digital instrument and how to determine correlation from a set of data Hypothesis Under uniformly high oxygen concentrations and at uniformly cool temperatures stoneflies in lower pH water will have a greater number of respiratory movements Lab Report Guidelines Pa Intro begins with broad topic that establishes relevance There is no direct quotation of sources Information is rewritten in your own words All sources of information are cited using correct format atthe end of each sentence containing the cited information End of Introduction deals with more specific topics The purpose section should identify the scientific and educational reasons for performing the experiment The hypothesis should be a concise statement predicting what you expect to find in the experiment Write this section in the future tense Page Irg 3 How to write a Procedures section The objective of the Procedures section is to describe the experimental procedure in sufficient detail for someone else to replicate the same experim2. measured in millimeters using calipers while viewing the tree sections under a microscope 5 Explain how calculations were performed For example The width of the tree rings was averaged for a 10 year span for all 9 trees The next page presents a comparison of lab manual instructions and corresponding procedures section of a lab report Lab Report Guidelines Page Irg 4 Do not include procedures that you did not perform Do not have numbered steps in your proce dure section Sample Procedures Section Original Lab Manual Procedure Estimating the relative length of each stage of mitosis For this procedure we will use permanently mounted slides of onion root These slides are prepared by slicing the roots into thin sections mounting them on microscope slides staining and then mounting under a cover slip Locate the meristem region of the root tip 1 Starting under the 10x objective find the region of active cell division l wer end of this region Recording data a Students should take turns as observer and recorder The tallied by the recorder in the results table Roles should be switched for the second slide Since prophase and as prophase Only count as prophase cells that contain distinctly visible chromosomes 1 Systematically scan the root tip moving upward and downward through column of cells 2 Tally each cell in a stage of mitosis that you observe being careful not to
3. paper versions of articles References to web pages only allowed for special assignments For some assignments you may be asked to search for information on the internet A reference for such information must include at a minimum this information in following order 1 Author of the web page or anonymous if author is not identified 2 Title of the web page from which the information was obtained Follow title with Internet 3 Name of organization that prepared the web page and when present the name of the company government agency or university that sponsors that organization Sometimes this can only be found by inspecting the URL 4 Date of page creation or last update date cited in brackets i e created 2008 May 15 cited 2008 Sep 14 Sometimes this can be obtained directly from the page or through the View Page Source option on the pull down menu 5 URL in parentheses of the page URL title and other information can be copied from browser to your document using the cut and paste functions Examples Franchesca P Kjeldsen K Hughey K Algae the forgotten treasure of tidepools Internet Department of Biology at Sonoma State modified 1997 May 23 cited 1998 Oct 5 http www sonoma edu biology algae algae html Matthews HS Lave LB Price setting for green design Internet The Green Initiative Carnegie Mellon University no date given cited 2008 Jun 18 http gdi ce cmu edu g
4. record the same cell twice Tally the 7 stages of 20 mitotic cells 3 Tally numbers in the table below Each group member should tally cells from a different slide Calculations 1 Pool your data with that of the class and then record the class totals in the table provided below 2 Calculate the percentage of cells in each stage 3 The relative time spent in each stage is equivalent to the percentage of cells found in that stage Lab Report Guidelines Rewritten as a lab report Procedures section Procedures Ae The relative time period of different stages of mitosis was determined using permanently mounted slides of stained onion roots tips Marietta College Biology Department 2011 rtm 4 Cells in different stages of mitosis were identified and counted as follows The permanently mounted onion root tip slide was scanned using a microscope under the 10X objective until a region of active cell division was located The cells were then viewed under the 40x objective The root tip was scanned for cells in mitosis by moving up and down columns of cells A assuring that each cell was recorded only once Each 7 time a cell in mitosis was found the stage was identified Only cells that had distinct chromosomes The cell counting procedure was repeated by a second individual who counted another 20 cells from a different slide Therefore we counted a total of 40 cells Calculations were performed for data pooled from
5. six separate counts of 40 cells The percentage of A cells in each stage was calculated and the relative length of each stage was equivalent to the percentage of cells in each stage Rewrite the original instructions in a clear logical and concise sequence The order instructions are given in the lab manual are not always the best for a Procedures section Page lrg 5 Each paragraph begins with a topic sentence All sentences are written in the third person passive voice Leave out unnecessary information such as where supplies were located in the lab Never repeat procedures Describe the basic procedure once and explain differences later as necessary Always describe how calculations were performed Lab Report Guidelines Page Irg 6 Procedures Sentence Rewrite Exercise Name Read the section on writing procedures before doing this exercise Rewrite each sentence so that they express the ideas clearly grammatically and using the third person passive voice 1 In the Rewritten Lab Procedures on the previous page there is a sentence written in the wrong tense Find the sentence and rewrite it correctly 2 I obtained 3 g of spinach leaves and ground them in a mortar and pestle Rewrite and explain why obtained is unnecessary 3 2 g of KCl and 2 g of NaCl were weighed out using the scale on the back bench and then each dissolved in 5 ml of H20 in separate test tube
6. Articles available online in pdf format but not HTML format are acceptable See discussion below about web resources While the specific format for references varies among disciplines however you must use the following formats for your lab reports Note about use of et al although et al is used in citations it should never be used in the full reference provided in the Literature Cited section all authors names must be listed in the order they occur in the original paper Publication year Publication year ees of book Reference from a book published McKinney M Schoch R 1998 Environmental science in and solutions a MA A Jones and Bartlett BUD Sper 988p x tor pages of pages n of pages an Chapter of an edited book Chapter Authors of chapter nanes vaadid ATA FE Crabb J Bamola P 1996 A new anepi oe to bud dormancy on woody plants Lae a Lang G editor Plant a age Wallingford Oxon GB CAB International p 83 113 Marietta College Biology Department 1996 Observation ethograms and wall seeking behavior In Introductory biology lab I manual Marietta OH Marietta College p 345 359 The lab manual can be used as a reference only if allowed by instructor Authors and Title of From a journal 1 and 2 sources I ySar of p ESEE a nuhlicnatian A k Smith AB Jones CD Banks EF 1994 Effects of absenteeism on student grades in biology American Journ
7. GUIDELINES FOR WRITING LAB REPORTS 1 All reports must be typed using a word processor on a microcomputer such as those available in the computer labs in the Rickey Science Center Use a 12pt font 1 margins all around and double space your text 2 Each student must write an independent lab report Lab partners are encouraged to discuss the results of lab exercises but each student must write a COMPLETELY INDEPENDENT report Plagiarism may be rewarded with a failing grade for the paper or the course at the instructor s discretion 3 Lab reports must follow the format outlined below and described on the following pages Introduction Background Information Purpose Hypothesis Procedures Results Tables and Figures Description of Data Discussion Conclusions Explanation of Results Future Experiment Literature Citations Grading of Lab Reports Your instructor will be asking the following questions while grading your lab report You should review these questions while writing and proofreading your report 1 Has the student read and followed the lab report guidelines 2 Does the report follow the correct format Is each section title clearly labeled 3 Are information and ideas placed into the appropriate sections 4 Be the report checked for grammar punctuation and speling 5 Have sources of information been correctly cited and referenced 6 Does the Background Information section present sufficient relevant backgroun
8. Stoneflies are insects that spend their larval stages in the water The larval stages which can last for up to 2 years Merritt and Cummins 1987 65 have been used as indicators of water quality in streams Surdick and Gaufin 1978 3 Stoneflies are normally found in association with clean water Hilsenhoff 1977 6 Hilsenhoff 1987 31 Although a number of factors affect their distribution the limiting factor in freshwater seems to be the availability of oxygen Olive and Smith 1975 34 Stonefly numbers are reduced whenever siltation Sm present Surdick and Gaufin 1978 8 It is hypothesized that the silt covers the delicate gills Hilsenhoff 1987 6 mayflies which also have delicate external gills are similarly affected Hubbard and Peters 1978 8 Stoneflies increase the flow of water over their gills in times of oxygen stress by doing a respiratory movement called push ups Merritt and Cummins 1987 67 What cues do the stoneflies use Is it a lack of oxygen in the water an increase in water temperature or a buildup of acid from respiration in their tissues that triggers respiratory movements Increasing temperature both increases respiration rates Schmidt Nielsen 1997 235 and decreases oxygen availability Smith 1990 203 Carbon dioxide is one product of respiration in the blood dissolved CO lowers pH Schmidt Nielsen 1997 235 pH is a measure of hydrogen ion concentration and ranges from 0 to 14
9. above put a period after the abbreviation of the last author remove the parentheses from around the year and place a period after the year and remove the excess capitalization from the title leave only the first word and proper names capitalized Place a period at the end of the citation Other online only journals should be treated similarly From state or federal documents Ohio EPA Ohio Environmental Protection Agency 1988 Biological criteria for the protection of aquatic life Volume II user s manual for biological field assessments of Ohio surface waters Columbus OH Ohio EPA 135p Smith RD Ammann A Bartoldus C Brinson MM 1995 An approach for assessing wetland functions using hydrogeomorphic classification reference wetlands and functional indices Wetlands Research Program Technical Report WRP DE 9 Vicksburg MS US Army Corps of Engineers Waterways Experiment Station 88p Lab Report Guidelines Page Irg 15 USDHHS US Department of Health and Human Services Center for Disease Control and Prevention 1993 Fluoridation census 1992 Atlanta GA CDC 686p Example Literature Cited section Literature Citations Hilsenhoff WL 1977 Using a biotic index to evaluate water quality in streams ann Technical Bulletin Wisconsin Department of Natural Resources Number E 132 22p Hilsenhoff WL 1987 An improved biotic index of organic stream pollution The Journal article Great Lakes Entomologist 20 31 39 Keet
10. al of nn Class Attendance 123 4 ER 23 Name of anrnai Lab Report Guidelines Page Irg 14 From a magazine 3 source which does not use volume numbers most DO Beckridge N 1997 The parasitic wasp s secret weapon Scientific American November 82 85 Note that for tertiary sources sometimes the month of publication substitutes for the journal volume number From an ONLINE ONLY Journal if the journal appears in print but you access it online use the format ABOVE and cite it as if you were looking at the print version If the journal is online only use the format BELOW Converting a PLoS ONE citation into our format Muscedere ML Traniello JFA 2012 Division of Labor in the Hyperdiverse Ant Genus Pheidole Is Associated with Distinct Subcaste and Age Related Patterns of Worker Brain Organization PLoS ONE 7 2 31618 doi 10 1371 journalljpone 0031618 remove Add period add sentence case period Muscedere ML Traniello JFA 2012 Division of labor in the hyperdiverse ant genus Pheidole is associated with distinct subcaste and age related patterns of worker brain organization PLoS ONE 7 2 e31618 doi 10 1371 journal pone 0031618 Add Period PLoS ONE is one of the new internet only journals There is no online equivelent so the formatting is different as well The citation as listed on the PLoS ONE site is close to our format You can cut and paste from the web site then make the changes shown
11. basis for the experiment and its results Near the end The variable tested and why it may have an effect What previous investigations have found How to use source information Never directly copy or quote sentences from your sources Ideas should be conveyed in your own words and the source of this information should be cited and referenced see description of Literature Citations below Purpose In a few sentences explain why the experiment was performed what was the scientific problem being studied and the objectives of the exercise There are usually a number of purposes to the lab exercise Some purposes are educational in nature such as to learn about experimental design Hypothesis Remember a hypothesis is one possible explanation of observations or information Whether your hypothesis is correct or not is irrelevant to your grade frequently the best lab reports are those that clearly explain why the hypothesis is incorrect The next page presents a sample Introduction section Lab Report Guidelines Page Irg 2 Sample Introduction section Section headings are Mec included Introduction gar Background Information Environmental pollutants have had dramatic effects on water quality of rivers and streams although the effects are not always obvious One lt approach is to monitor the numbers of certain aquatic insects that are sensitive bioindicators of water quality Surdick and Gaufin 1978 3
12. d information 7 Has the 3 person passive voice been used consistently in the Procedures and Results sections 8 Are the correct types of information placed in the Description of Data and Explanation of Results sections 9 Have the results been thoroughly explained in the Discussion section Lab Report Guidelines Page Irg 1 How to write an Introduction section The Introduction section should include the following three sections Remember to use a 12pt font 1 margins all around and double space your text Background information This section presents information that familiarizes the reader with the subject of the experiment What to include A well written introduction should present information about all the topics directly pertinent to the experiment The Introduction section of the lab exercise provides a brief summary of many of the relevant subjects How to write Use well structured paragraphs beginning with a topic sentence that expresses ideas in your own words How to organize Organize the information from the broadest topics that help to establish relevance to more specific topics pertaining directly to the experiment For example the paragraphs might be sequenced to explain First Why a nonscientist would be interested in the topic e How the topic relates to human concerns Later The type of organism used in the study and why Background information on topics the reader should know to understand the
13. d Research price html Anonymous Algal bioassays nutrient testing Internet Bureau of Laboratories Florida Department of Environmental Protection modified 2005 Feb 1 cited 2007 Aug 9 http www dep state fl us biology biol aalimnut htm Lab Report Guidelines Page Irg 17 Lab Report Guidelines Page Irg 18
14. ent The instructions provided in the lab manual should not be copied verbatim they should be rewritten to provide the essential elements of the procedure leaving out trivial details Essential elements of a Procedures section 1 Sentences should be written in the third person passive voice Incorrect I measured the number of tree rings in cross sections of 9 spruce trees This sentence uses the first person active voice Correct The number and width of tree rings were measured in cross sections of 9 spruce trees This sentence uses the third person passive voice This style of writing is used to convey that the researcher was impartial and objective when performing the experiment and collecting the data 2 All procedures should be presented clearly and accurately The instructions of the lab manual should be rearranged to form well structured paragraphs 3 Include all parts of the procedure that you performed leaving out unnecessary trivial details Incorrect obtained 10 grams of NaCl from the front bench and dissolved it in 250 ml of water in a glass beaker The data were recorded in a table All of the underlined information is unnecessary Correct Ten g of NaCl were dissolved in 250 ml of water It is assumed that data are recorded Note also that a sentence should not begin with an arabic number 1 e 10 4 Explain precisely how the data were collected For example The width of the tree rings was
15. ent i If the number of stomata does allow for more photosynthesis then we should be able to measure this The increase in photosynthesis could be measured directly or by comparing the size and weight of the plants Lab Report Guidelines Page Irg 12 How to write Citations and References It is essential that you identify ALL sources of information and ideas included in your report Do not be misled into believing that citations are only required for direct quotes As stated above sources should not be directly quoted in a lab report You must however cite the sources of information and ideas that you express in your own words More information about citations and references can be found at http www marietta edu biol library citation html 1 Citations Citations within the text of the report point to the original source of information and are most commonly used in the Background Information and Explanation of Results sections Footnotes or subscripts are not used to cite sources in scientific writing Although the format used for citations varies among disciplines the Biology Department requires the following format for all assignments Author s year of publication page If the source has a single author then the citation is written as For example Smith 1992 97 If the source has two authors then the citation is written as For example Smith and Jones 1997 184 If the source has three or more authors the abbr
16. etc Decimal numbers should always have at least one numeral before the decimal point 0 47g not 47g Superscripts and subscripts should be used when needed for example 25 C 80cm and H 0 2 There are two sub sections of the Results I Tables and Figures Presentation of data in properly structured graphs and tables IL Description of Data This is a paragraph structured description of the data in effect narrate to the reader 3 Characteristics of Tables and Figures A correctly prepared graph should 1 be sequentially numbered Figure 1 Figure 2 etc 2 have a descriptive title 3 have the independent variable on the x axis 4 possess clearly labeled axes 5 have data points that are clearly marked A correctly prepared table should 1 be sequentially numbered Table 1 Table 2 etc 2 have a descriptive title 3 have rows and columns clearly labeled 4 The Description of Results section should Be written in the third person passive voice e Describe the key features and trends that you perceive in the data presented in the figures and tables Not interpret the data Explaining what the results mean or why the results occurred is done in the Discussion section of the lab report Lab Report Guidelines Page Irg 9 Examples of a correctly prepared Graph and Table Figure 1 Oxygen uptake by barley seeds Prem measured at different temperatures ex oS E 5 Data points clearly marked 8 4 ne and connec
17. eviation et al is used after the first author s name For example Smith et al 1997 184 Proper Use of Citations 1 Citations must be accurate to the source of information to the indicated article and page 2 Citations should refer to a single page This is not acceptable Jones 1997 23 25 If the referenced information begins on one page and continues on the next just cite the first page If distinct information is being cited from several pages a different citation must be used for each 3 Do not cite from abstracts cite only from the full text of an article 4 Do not cite only at the end of paragraphs citations should be included throughout a paragraph to prevent ambiguity as to the source of information 5 Every citation must also be listed in the Literature Cited every source in the Literature Cited but actually be cited in the text For examples look at the sample Introduction amp Discussion sections above Lab Report Guidelines Page Irg 13 2 References Citations point to references listed in the Literature Citations section of the lab report where the sources of the information are listed alphabetically For Intro level courses acceptable sources include scientific articles published in books science magazines and scientific journals The course textbook and lab manual should only be used when specifically allowed by your instructor Do not use mass media magazines and newspapers
18. knowledge from cited literature sources about the topic 4 Future experiment This section shows how well you understand the experiment and its results In no more than two paragraphs explain how another experiment might help to answer questions raised by the current experiment Usually the results of one experiment provide the basis for future related experiments possibly in which other variables are studied Be sure to state the purpose of the future experiment but do not include a lengthy description of procedures Lab Report Guidelines Page Irg 11 Comparison of Description of Data and Discussion abbreviated examples Results Description of Data The number of stoma per unit area in response to light intensity was determined Figure 1 Effect of light intensity on stomatal density Stomatal density mm 300 Soybean leaves were grown from seedlings 250 under light sources of different intensities for 200 3 weeks Between light intensities of 1000 150 4 and 7500 Lux the density of stomata 100 increased about 5 fold Figure 1 Between 50 J light intensities of 1000 and 5000 lux the stomatal density increased somewhat linearly to about 225 stoma mm Above 5000 lux 0 2000 4000 6000 8000 A the stomatal density tended to level off Light intan siy TUN around 250 stoma mm Discussion Conclusions The data did not support the hypothesis that increasing light intensity would cause a decrease in
19. nd 95 of the control respectively Lab Report Guidelines Page Irg 10 How to write a Discussion section 1 The Discussion section includes three subsections Conclusions Explanation of results Future experiment 2 Conclusions In a sentence or two state whether the hypothesis is supported by the results or not Identify any other conclusions pertaining to the hypothesis based upon the results of the experiment 3 Explanation of Results In this section you should explain and interpret your results and relate your results to information presented in the Background Information section and to other literature sources What are interpretations of results Explanations of why or what caused the results to occur and or why did the results supported or contradicted the hypothesis As stated above an incorrect hypothesis will not tarnish your lab report so you should explain the discrepancy based upon biological principles e Suggestions and proposals of new biological principles and relationships Comparing and contrasting with results and conclusions of previous studies Interpretations of results should draw upon and cite information from the literature sources and should not be vague unfounded notions that happen to pop into your head A poor Explanation of Results focuses on for example experimenter errors as a substitute for actually discussing the scientific meaning of the results in context of prior
20. on WT Gould JL Gould CG 1993 Biological science 5th ed New York NY Textbook W W Norton amp Co 1194 p 3 source Kharman GIA Frankel LP Jackson JJ 2002 Effects of acid deposition on two Adirondack streams New York Academy of Science Proceedings 86 341 Journal article 347 Merritt RW Cummins KW Eds 1987 An introduction to the aguatic insects Book of North America 2nd ed Dubugue IA Kendall Hunt Publ Co 722 pp 2 Surdick RF Gaufin AR 1978 Environmental requirements and pollution tolerance of Plecoptera U S Environmental Protection Agency Document 600 4 78 062 Government document Lab Report Guidelines Page Irg 16 Use of Web Resources References to web pages i e HTML are not allowed in lab reports or term papers Web pages are notoriously short lived and a reference to a specific URL today is likely to not work or no longer provide the referenced material in the near future In general if you print an online article and a URL is included at the top of the page and or the page numbers begin at 1 even though the article reference gives a different first page number and or there are hyperlinks to the figures and tables then you are looking at an HTML version of the article If you are asked to do literature research on line articles in pdf format can be used because they retain the same formatting as the original print version Pdf articles can be cited as described above for
21. s This sentence is excessively wordy with unnecessary trivial details and grammatically incorrect Rewrite fixing all of the problems 4 Place iodine on the slide stain the sample for I minute This sentence uses the wrong tense and has a comma splice two independent clauses need a conjunction or to be separate sentences 5 This procedure sought to count the number of algae in the sample Procedures do not seek to do things 6 1 The instructor prepared the yeast suspension 2 The sample was to be viewed under the 40x objective of our microscope 3 We placed a drop of the yeast sample on a microscope slide Reorganize remove numbering and unnecessary information and rewrite as a single sentence using correct tense 7 We counted the number of cells in 12 squares and recorded the number in the table Rewrite and explain why and recorded the number in the table is unnecessary Lab Report Guidelines Page Irg 7 Lab Report Guidelines Page Irg 8 How to write a Results section The scientific data is presented in this section This includes both qualitative observations and quantitative measurements You should include any observations that have bearing on the interpretation of the results interpretation of the data are presented in the Discussion section Essential elements of a Results section 1 Numbers should never stand alone they must be accompanied by appropriate units e g ml cm cm sec
22. ted by a line 3 2 Ag 1 a 0 Titles and units 10 15 20 25 n P h topi presented for X and Temperature C aragraph topic Y axes sentence The description of this data might be e Figure 1 presents the uptake of oxygen by barley seeds over a five minute period Temperatures tested ranged from 0 to 25 degrees Celsius At the lowest temperature no oxygen uptake occurred As the temperature was increased oxygen uptake by the seeds increa ed in a linear fashion to a maximum value of 5 ml O at 25 C Description of key values and trends Table 1 Effect of different pollutants else on Chlorella ofcells of Ecosystem 10 ml control Ee Headings neatly formatted control 20 Re pollutant 1 23 115 pollutant 2 3 15 pollutant 3 10 50 ollutant 4 19 95 P Paragraph Topic It is OK to include sentence some procedures to clarify the results The description of this data might be r E The effects of the four pollutants on algal cell growth was also investigated The number of Chlorella cells remaining after twenty days growth with each pollutant is shown in Table 1 The control grown in spring water only contained 20 x10 cells per ml Pollutant 2 had the most dramatic effect reducing the cell count Br 3x10 cell ml 15 of the control Pollutant 3 reduced the cell count to 10x10 D an pi 2 cells ml 50 of the control Pollutants 1 and 4 had very little if any effect en yielding 115 a
23. the number of stomata Instead between 1000 and 5000 lux the stomatal density increased A i X proportionally with the light intensity Conchisionvrelativete typuthesi Explanation of Results It was expected that light intensity would cause a decrease in the number of Proposed stomata Instead the opposite relationship was observed figure 1 Itis possible ae n that the increase in the number of stomata was due to an increased rate of u photosynthesis The function of stomata is closely related to photosynthesis Mesophyll cells Literature sources are the most important cells for photosynthesis in the leaf and need a source of to support CO Raven et al 2008 737 Somata form pores in the leaf to allow exchange _ explanation of CO and water through the leaf cuticle layer to the underlying mesophyll cells Buchanan et al 2000 651 Photosynthesis also increases as the amount of light increases Rabinovich and Govingee 1995 223 and it is possible that more stomata allow higher rates of photosynthesis to occur previous research Other researchers have reported that stomatal density corresponds to other environmental factors such as humidity and CO concentration Fraser et al 2008 773 Furthermore mutant plants with abnormally high numbers of Future experiment stomata were observed to have higher rates of photosynthesis builds upon results of this one Future experim
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