Plant Health Instructor consists of the peer-reviewed parts of the APSnet Education Center. Materials accepted for publication must be scientifically sound, suitable for the designated audience, and prepared according to the guidelines provided by the links below. A checklist is also provided to assist authors. If accepted, authors must transfer copyright to the APSnet Education Center. Accepted materials will be placed in the appropriate section of the Education Center and cited as a publication in the peer-reviewed APS journal, The
Plant Health Instructor.
Prospective authors are strongly encouraged to contact the Editor-in-Chief, Chris Little, at
firstname.lastname@example.org to discuss their plans, in order to avoid duplication and encourage coordination with others who may be preparing similar materials.
Why submit your instructional materials to the APSnet Education Center?
Publication in the APSnet Education Center benefits both students and instructors. Instructors receive recognition for their contributions to education, which are peer reviewed. APS provides technical support and image resources, so authors can focus on content and presentation. The APSnet Education Center provides outreach to K-12 teachers as well as instructors and students in plant pathology, biology and microbiology courses. Instructors can choose from the many freely accessible online materials to enrich their own courses. Teaching Notes and articles provide a means to contribute to the scholarship of plant pathology pedagogy.
Students have access to quality instructional materials created by a variety of instructors with expertise in many areas. Plant pathologists who never enter a classroom can contribute their knowledge and insights to students worldwide by publishing materials in the APSnet Education Center. Specialists in other disciplines can provide information on topics with plant pathology applications. The APSnet Education Center also may be used for continuing education. Plant health professionals and extension clientele can review basic knowledge and update their education in quickly changing areas. Online, peer-reviewed publication assures accurate and current information with color images and other instructional technologies not available in traditional textbooks.
K-12 Teachers Guide: Exercises related to plant pathology that are appropriate for K-12 classrooms. The information should provide sufficient background for understanding by K-12 teachers and follow the established format of published exercises in the K-12 section of the APSnet Education Center. Submissions should indicate the recommended grade levels and preparation needs for each exercise. Authors should suggest sources of materials as needed. A list of relevant key words not listed in the title should be included to aid searches.
Plant Disease Lessons: Plant Disease Lessons are designed for students in higher education with a basic background in biology, but no specific knowledge of plant pathology. They follow the established format of previously published lessons including sections on Symptoms and Signs, Pathogen Biology, Disease Cycle and Epidemiology, Disease Management, Significance (biological, economic, historical), and Selected References. Select recent or recently updated lessons as examples. The References should be appropriate for the intended audience. Images are encouraged. Images may be provided by the author or chosen from previously published APS images (see Publication Preparation guidelines). Authors may request artwork support for production of the disease cycle. Authors should indicate which drawings from the disease cycle should accompany the text sections explaining the cycle. See published lessons for examples. A list of relevant key words not listed in the title should be included to aid searches.
If an author would like to include detail that may go beyond what introductory students should be expected to read, discuss it with the Editor-in-Chief; it could be made into a separate page with “additional information” that would be available for more advanced audiences.
Laboratory exercises: There are two categories of laboratory exercises: Introductory and Advanced. Introductory laboratories assume no previous experience in plant pathology and should be appropriate for introductory or general plant pathology courses that are usually at the undergraduate level. These laboratories also may be useful for biology and microbiology survey courses or for advanced high school courses. Advanced laboratories are designed for courses that have a previous plant pathology course as a prerequisite and usually assume some background in basic plant pathology.
Follow the established format in the Introductory and Advanced Laboratory Exercises sections of the APSnet Education Center. Images and appropriate background material are encouraged. Include "instructor notes" appropriate for novice instructors and faculty of biology or microbiology departments who may benefit from guidance in obtaining cultures or living materials, preparation time, specialized equipment, etc. A list of relevant key words not listed in the title should be included to aid searches.
Topics in plant pathology: There are two categories of Topics in Plant Pathology: Introductory and Advanced. Introductory topics assume no previous experience in plant pathology and should be appropriate for introductory or general plant pathology courses that are usually at the undergraduate level. Advanced topics are designed for courses that have a previous plant pathology course as a prerequisite and usually assume some background in basic plant pathology. Examples include diagnostics, epidemiology, host-parasite interactions, molecular biology, and pathogen-specific specialty courses. There is no established format for Topics in Plant Pathology, but the text should be scientifically sound, address a specific topic fully, and include images and appropriate references. A list of relevant key words not listed in the title should be included to aid searches.
Instructor Communication and Scholarship: The purpose of the section is to provide an avenue for peer-reviewed publication of teaching scholarship related to plant pathology. Publication may be in one of two categories:
Teaching Notes- Short communications on classroom and/or laboratory techniques and methods. These are intended to encourage instructors to share ideas and techniques that will benefit other instructors, but do not warrant a full length teaching article. Examples include: reliable laboratory techniques for molecular plant pathology, laboratory ideas for use by biology and microbiology instructors who would like to include plant pathology in their courses, new instructional approaches to aid students with difficult concepts, games or other novel teaching methods. They may be appropriate for general courses or specific courses at any level from K-12 through higher education. Each communication should explain clearly what is recommended including sources of materials when needed, preparation timing, the potential benefit to the students and/or instructor, and any potential problems or limitations. Teaching Notes may not exceed 3500 characters and may include up to two images. Key words or phrases that do not occur in the title may be included to aid in searches. Sample terms include: diagnostics, epidemiology, games, group learning, host-parasite interactions, inquiry-based learning, instructional technology, K-12 instruction, molecular plant pathology. Include no more than four references to teaching or plant pathology publications as appropriate.
Teaching Articles- Manuscripts should be scholarly articles related to the teaching and learning of plant pathology. Images are encouraged. The articles can focus on the instructor’s role as an educator through discussion of techniques, philosophy, methods, classroom interactions, and leadership. Manuscripts may address the role of plant pathology in nontraditional courses and the participation of plant pathologists as instructors in such courses. Additional topics include discussion of changes to maintain up-to-date content in plant pathology courses, appropriate preparation of plant pathology students for available positions, fostering critical thinking and creativity, and ethical issues in science and technology. Manuscripts should be based on research in teaching and learning in which the experience is examined through a theoretical framework that explores the implications of the subject with supporting documentation. Key words or phrases that do not occur in the title should be included to aid in searches. Sample terms include: diagnostics, epidemiology, games, group learning, host-parasite interactions, inquiry-based learning, instructional technology, K-12 instruction, molecular plant pathology.
Manuscripts should be designed as teaching resources to engage students in scenarios related to any aspect of plant disease management or plant health management. Case studies can be prepared for use by students at the graduate, undergraduate, high school, or elementary school level; the targeted educational level for the case should be specified. A case study creates a scenario mimicking real-life situations but with fictional names of protagonists. It places students in the role of a decision maker (farmer, crop consultant, nursery manager, extension professional, etc.) faced with a challenging problem in plant disease or plant health management for which there is no simple solution, but rather a set of alternative strategies that each has advantages and disadvantages. The case describes the management challenge, helps students to understand why the challenge must be met by the decision maker, explains what the management options are, and provides background information as well as links to additional resources. A separate section of the case provides resources for instructors, including suggestions for using the case in classrooms and questions for stimulating class discussion. Cases should be conducive to development of critical thinking skills, inquiry-based learning, and group discussion. They should also be well illustrated (photos, line drawings, etc.). When submitting a case study manuscript, authors must provide evidence that the case has already been tested in an appropriate-level classroom and explain how the manuscript was modified as a result of feedback from the students. Keywords that do not occur in the title should be provided to aid in web searches. Sample terms include: active learning, critical thinking, inquiry-based learning, instructional technology, plant pathology, plant health management, and case studies. For examples of case studies published in
Plant Health Instructor, please
Other: Authors with materials that do not seem to fit the above categories should contact
Chris Little, Editor-in-Chief, at email@example.com to discuss an appropriate outlet for their teaching scholarship in the APSnet Education Center. Entire courses, which may be tuition-based, submitted by individuals or groups are also encouraged.
Upon submission, the material is forwarded to the appropriate Senior Editor who notifies qualified reviewers. Materials submitted may be placed in a secure offline site for review. In other cases, images will be placed in an offline review site, and accompanying text will be sent to reviewers. Reviewers have 3 weeks to review the submission and to recommend to the Senior Editor acceptance, rejection, or acceptance with revisions. Reviewers may be chosen for content review and/or for instructional review at various levels.
If material is rejected, the author may ask the Senior Editor to reconsider the decision and, if not satisfied with the Senior Editor's response, may appeal to the Editor-in-Chief (EIC), whose decision is final.
If the material is accepted with revision, the Senior Editor notifies the author. Authors should then respond to any suggested changes and send a modified version to the Senior Editor within eight weeks. In a cover letter or email message, the author should explain how major criticisms were dealt with and why, if any, criticisms were not accepted. Unless authors have permission from the Senior Editor for a brief delay in revision, material requiring more than eight weeks for revision should be sent to the EIC as a new submission.
The revised material will be reviewed by the Senior Editor and, if judged acceptable for publication, will be forwarded to the EIC who will then forward it on to APS Headquarters. Following copyediting, the material will be posted in the APSnet Education Center. The date of posting, which will be listed on the material with the
Plant Health Instructor digital object identifier (doi), will be the official publication date.
Authors who wish to publish in the APSnet Education Center must be willing to act on the recommendations of reviewers and editors. The editors provide competent and fair review for every manuscript and aid authors in presenting information in a style appropriate to our audience. Suggested revisions that substantially change the author's intent or appear to be in error may be rebutted with documented explanation in an e-mail or cover letter to the editor when the revised manuscript is returned.
Initial submissions of materials should be in electronic form, but the Education Center/The Plant Health Instructor, unlike other APS journals, does not use the Manuscript Central service. Text for materials with scanned images should be e-mailed as attachments to
firstname.lastname@example.org or mailed on CD-ROM, or with slides, drawings, and/or print negatives and prints to:
Christopher R. Little • Editor-in-Chief • The Plant Health Instructor
Plant Pathology Dept. • Kansas State University
4024 Throckmorton - Plant Science Center • Manhattan, KS 66506 • Email:
Office: (785) 532-1395 • Fax: (785) 532-5692.
All submissions must be accompanied by an e-mail message or cover letter containing the following information:
- Title of material
- Type of material (K-12 News, K-12 Teacher Exercise, Plant Disease Lesson, Laboratory Exercise, Topic, Teaching Note, Teaching Article, etc.)
- Name, title, affiliation, e-mail and mailing address, telephone and fax numbers of corresponding author.
- List of attached documents by filename and title. A large number of files may be best “bundled” into a zip file.
- List of attached files by figure number (if included).
- A statement that all authors have reviewed the manuscript and approved its submission to the APSnet Education Center
- For search purposes, include key words not included in the title.
If emailing, expect acknowledgement within 48 hours; otherwise, please follow up with a phone call or mail to guard against loss of emailed materials.
Authors should view current materials published on the site for general guidelines on article style, length and content (see also Publication Categories section). Submissions following established models (K-12 teacher exercises, plant disease lessons, and laboratory exercises) are best submitted as word processing (preferably .rtf or .doc) files with images as described below. Submissions that do not follow these formats will be returned to the author for revision before they are sent out for review. Authors with good html and web-authoring skills may prepare files for online review.
The APSnet Education Center can provide technical support for preparation of online instructional materials including scanning of images, artwork for disease cycles, and preparation of online versions of submissions. If authors require specialized technical support, they should contact the Editor-in-Chief.
Illustration files should
not be merged or linked to the text file, but submitted as separate files; references to illustrations or small images within the body of the text should be used to determine their placement. Captions for figures should be placed in a list at the end of the text, following the references. Each table should be placed on a separate page following the references. Prepare tables in the table format with one data field per cell. Double-space the entire document (including tables), and use a 12 point font. Microsoft Word (.doc) or Rich Text Format (.rtf) are the preferred file formats for text. Contact the Editor-in-Chief if other formats are desired.
File names for text files should be the last name of the corresponding author and the appropriate extension (e.g., Smith.doc). File names for all illustrations should be corresponding author name, followed by the appropriate figure number and the appropriate extension, (e.g., Smith1.jpg, Smith2.jpg, Smith3.jpg).
Images may be submitted as:
Print negatives (a print negative must be accompanied with a print for comparison)
Scanned images.NOTE: Minimum size: 450 to 500 pixels on the longest size of the images. File format: jpg at maximum quality (APS will compress and reduce the size of the image as necessary). Procedure: Have image scanned on excellent equipment by someone with scanning experience. Very little image enhancement or sharpening is best (once overdone, it is impossible to go back).
If files are submitted on CD-ROM, the CD should be clearly labeled with the first author's name and
Plant Health Instructor. When saving the file, prepare the manuscript as for review, omitting any line numbering. Figures and tables should not be inserted into manuscripts. Prepare tables in the table format with one data field per cell.
General Style Manual
Title. Unless otherwise indicated, all materials submitted for publication in the APSnet Education Center (and cited as a publication of the
Plant Health Instructor) must have a title that is descriptive of the subject.
Authors. List all authors by their full names, e.g., Jane E. Doe, (unless the author uses initials only) and provide their affiliation including title, department, institution, or company, and location.
Acknowledgments. Acknowledgments may be included with Topics in Plant Pathology or Teaching Articles after the text and before the "Literature Cited" or "Selected References." Authors may acknowledge any financial or other assistance associated with the work reported or the development of the material.
Abbreviations. Avoid nonstandard abbreviations in text. These may be used in tables (see below).
Apparatus and materials. Names of unusual proprietary materials and special apparatus should be followed by the manufacturer's name and address in parentheses (city and state [United States] or country). It is only necessary to cite these materials by specific name if the work cannot be otherwise replicated. Trade names may be used and should be capitalized; trademark symbols should not be used.
Common names of plant diseases. Use Common Names of Plant Diseases (1) for the accepted common name of a disease.
Chemical terms. List pesticides by their approved common or generic names. Brand names may be included parenthetically when a pesticide is first mentioned. The current
Farm Chemicals Handbook (2) and the most recent edition of
Acceptable Common Names and
Chemical Names for the
Ingredient Statement on Pesticide Labels (5) are good sources. Use the chemical name if a common name is not available. The
Merck Index (4) and
Hawley's Chemical Dictionary (11) are good sources for checking spellings of chemical terms.
Scientific names. Authorities for Latin binomials. Citation of authorities for Latin binomial names is optional and not usually recommended. When used, authorities should be given only at first mention of the primary organisms discussed (hosts and causal agents). After first use of binomials, the name can be written by abbreviating the genus, e.g.,
Phytophthora infestans. For trinomials, the name can be written by abbreviating the genus name and spelling out the specific epithet and subspecific epithet, e.g.,
P. graminis f.sp.
Bacteria. Spell names according to
Bergey's Manual of Systemic Bacteriology (10), the Approved List of Bacterial Names (14), or the List of Prokaryotic names with Standing in Nomenclature. Some names in the older publications may be out of date. Designations below the level of subspecies should be italicized. Where applicable, designate strains.
Fungi. The preferred sources for common and scientific names and authorities of fungi are
Fungi on Plantsand Plant Products in the United States (6),
Dictionary of the Fungi, (9), or the CABI databases.
Insects. Common Names of Insects and Related Organisms (15) can be used to verify insect names.
Plants. Farr et al. (6) is a good source for spelling of common and scientific names. Other good sources are
Merriam-Webster's Collegiate Dictionary (19),
A Checklist of Names for 3,000 Vascular Plants ofEconomic Importance (17), and
The Plant-Book (12). Regional floras may be used. Use the term "cultivar" for agronomic and horticultural varieties. Identify the source of cultivars and include CI and PI numbers when appropriate. Enclose the name of a cultivar in single quotation marks only when it immediately follows the botanical name.
Viruses. Guidelines for virus names can be found
here. Searchable lists of virus names are available at
In formal taxonomic usage, virus family, subfamily, and genus terms should be capitalized and italicized with the name of the taxon preceding the taxonomic unit (18). The full name of the virus should be in italics with the first word capitalized. For example, "Family
Brome mosaic virus" and "Genus
Southern bean mosaic virus." In vernacular use, the virus family, subfamily, and genus, (and species) should be lowercase, not italicized, and the name of the taxon should follow the term for the taxonomic unit, e.g., the "bromovirus genus." The name of the taxon should not include the formal suffix, e.g., "the bromovirus family," not the "bromoviridae family."
Software. Software used should be treated as a proprietary material or apparatus. Give the manufacturer or developer name in parentheses with location (city and state or country). Software such as that produced by SAS should not be cited in literature citations.
Statistics. Describe statistical methods with enough detail to enable the reader to verify the reported results. Always specify the experimental design and indicate the number of replications, blocks, or observations. Identify the computer program used to analyze data if appropriate. When a quantitative factor (e.g., temperature) is studied, it often is desirable to use regression instead of analysis of variance. For qualitative factors (e.g., cultivar), analysis of variance and mean separation tests can be used, but the specific procedure and significance level should always be indicated. Whenever possible, researchers should consult a statistician before designing an experiment and when analyzing results. For more information see Johnson and Berger (9), Madden et al. (13), Swallow (16), and Gilligan (7).
Units of measurement. Information may be published in either English or metric units of measure. In choosing a system of units, authors should consider the needs and preferences of the intended audience. For example, both metric and English units are provided for distance, size, and temperature in the K-12 and Introductory sections.
Units of time. Day is never abbreviated. Week (wk), month (mo), and year (yr) are abbreviated only in tables. Second (s), minute (min), and hour (h) are always abbreviated if preceded by a numeral.
Literature cited. References should be cited in the text by author and year. Always cite the original source of publication, whether print or on-line. List references in alphabetic order by authors' surnames. When citing multiple works by the same author, list articles by one author before those by several authors. Determine the sequence by alphabetizing the first author's surname and coauthors' surnames, by the year of publication (most recent last), and if necessary, by the page numbers of articles published in the same journal. Italicize Latin binomials, capitalize German nouns, and insert diacritical marks as needed. List specific pages of books. Authors are encouraged to spell out names of journals, but if they desire to abbreviate titles, abbreviations listed in the
BIOSIS List of Serials (3) must be used.
Check the accuracy of each citation and that each is cited in text. Only references generally available should be listed in Literature Cited or Selected References. Do not cite work that is in preparation or submitted but not accepted for publication. References should be appropriate for the audience of the material.
On-line publications. Materials originally published on-line by established sources should be cited as published on-line. The printed version of publications that were originally published in traditional print form but which were also available or referenced on-line should be cited as print publications. Citation of on-line material should include author(s), date, title, publication name or sponsoring organization, and publication number or equivalent identifier, if any, e.g.:
Schumann, G.L. and C. J. D’Arcy. 2000. Late blight of potato and tomato.
Plant Health Instructor. On-line doi: 10.1094/PHI-I-0724-01
Include the electronic address of the material, although electronic addresses and locations are frequently changed. If information used in text can be found on-line but is not from an established publication, it should be referenced in text as a personal communication (requiring the same verification from the authors as any other personal communication), e.g., (J. Jones, B. Myers, and P. Johnson, personal communication). On-line software, programs, models, etc. that are used to analyze data should be cited in text by referencing the sponsoring organization and program, e.g., NIH Image is available on-line from the National Institute of Health.
Authors may use images from other APS publications, such as Compendia and slide sets, for their materials if they are cited as (Courtesy J. Smith). Note the original publication, edition, figure or plate number, page number, and credit (e.g. Courtesy J. Smith) in the list of figure captions. If an image indicates that it is "Used by permission of," APS does not hold the copyright. A request to use the image must be made by the author to the original source.
Permission must be granted for use of copyrighted materials. Copyright forms must be signed for all images and illustrations.
Downloadable file for copyright transfer.
Downloadable form for obtaining permission to use previously published materials.
Cite all figures in numeric order in the manuscript. To facilitate editing and review, provide a list of figures and captions at the end of the manuscript after the references. Email images as attachments or mail on CD-ROM or as slides, drawings or print negatives (with print). APS can scan images and drawings for the authors. The storage medium can be returned to the author. Image files must be named for the corresponding author, followed by the appropriate figure number and the appropriate file extension, (e.g., Smith1.jpg, Smith2.jpg). The storage medium must be labeled with
Plant Health Instructor and first author's name. Unusable files may result in delays in publication.
American Phytopathological Society Committee on the Standardization of Common Names for Plant Diseases. 1994. Common Names for Plant Diseases. APS, St. Paul, MN.
Anonymous. (Current) Farm Chemicals Handbook. Meister Publishing Co., Willoughby, OH.
BIOSIS. (Current) Serial Sources for the BIOSIS database. BIOSIS, Philadelphia, PA.
Budavari, S. 1989. The Merck Index. 11th ed. Merck & Co., Rahway, NJ.
Environmental Protection Agency, Pesticide Regulation Division. (Current) Acceptable Common Names and Chemical Names for the Ingredient Statement on Pesticide Labels. EPA, Washington, DC.
Farr, D. A., Bills, G. F., Chamuris, G. P., and Rossman, A. Y. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul.
Gilligan, C. A. 1986. Use and misuse of the analysis of variance in plant pathology. Pages 225-261 in Advances in Plant Pathology, vol. 5. Academic Press, New York.
Johnson, S. B., and Berger, R. D. 1982. On the status of statistics in phytopathology. Phytopathology 72:1014-1015.
Kirk, P.M., P.F. Cannon, D.W. Minter, and J.A. Stalpers. 2008. Ainsworth and Bisby's Dictionary of the Fungi. 10th edition. CABI, Wallingford, UK.
Krieg, N. R., and Holt, J. G., eds. 1984. Bergey's Manual of Systemic Bacteriology. Vol. 1. Williams and Wilkins, Baltimore, MD.
Lewis, R. J., Sr. 1993. Hawley's Condensed Chemical Dictionary. 12th ed. Van Nostrand-Reinhold, New York.
Mabberley, D. J. 1987. The Plant-Book. Cambridge University Press, Cambridge.
Madden, L. V., Knoke, J. K., and Louie, R. 1982. Considerations for the use of multiple comparison procedures in phytopathological investigations. Phytopathology 72:1015-1017.
Skerman, V. B. D., McGowan, V., and Sneath, P. H. A., eds. 1980. Approved Lists of Approved Bacterial Names. 2nd ed. American Society for Microbiology, Washington, DC.
Stoetzel, M. B., ed. 1989. Common Names of Insects and Related Organisms. Entomological Society of America, Lanham, MD.
Swallow, W. H. 1984. Those overworked and oft-misused mean separation procedures—Duncan's, LSD, etc. Plant Dis. 68:919-921.
Terrell, E. E., Hill, S. R., Wiersema, J. H., and Rice, W. E. 1986. A Checklist of Names of 3,000 Vascular Plants of Economic Importance. USDA Handb. 505.
Van Regenmortel, M. H. V., Fauquet, C. M., Bishop, D. H. L., Carstens, E., Estes, M., Lemon, S., McGeoch, D., Wickner, R. B., Mayo, M. A., Pringle, C. R., and Maniloff, J. 1999. Virus Taxonomy. Seventh Report of the International Committee for the Taxonomy of Viruses. Academic Press, New York.
Webster's 10th New Collegiate Dictionary. 1994. Merriam-Webster, Springfield, MA.
Checklist for Submission to the APSnet Education Center
- Double-spaced (including tables), 12 point font.
- Material has not been published previously or simultaneously submitted elsewhere.
- Manuscript has been critically reviewed by colleagues.
- Formatted as Microsoft Word 2004 or earlier, Rich Text Format, or other acceptable format.
- File names for text files are the last name of the corresponding author plus the appropriate extension (e.g., Smith.doc).
- File names for all illustrations are the last name and figure number followed by the appropriate extension (e.g., Smith1.jpg, Smith2.jpg.)
- Plant Disease Lessons, K-12 Teacher Exercises, and Laboratory Exercises follow the format of previous publications in the APSnet Education Center.
- Teaching Notes do not exceed 3500 characters, including author names, affiliations, "Literature Cited," etc.
- Authors listed under the title with full names and affiliation including department, institution, or company, and location.
- References are cited in the text by the author-and-year method.
- All references are listed in alphabetical order by authors' surnames.
- Double-checked the accuracy of each citation and that each is cited in the text. Selected references do not need to be cited in the text.
- Cite tables in numeric order in the body of the manuscript; explain any nonstandard abbreviations in table footnotes.
- Captions for figures are listed following "Literature Cited" or "Selected References." For previously published images, include source information.
E-mail message or cover letter will be included containing the following information:
- Title of material
- Type of material (K-12 News, K-12 Teacher Exercise, Plant Disease Lesson, Laboratory Exercise/introductory or advanced, Topic/introductory or advanced,Teaching Note, Teaching Article)
- Name, title, affiliation, email and mailing addresses, telephone and fax numbers of corresponding author.
- List of attached illustrations by figure number and filename (e.g., Smith1.jpg, Smith2.jpg, etc.).
- Include a statement that all authors have reviewed the manuscript and approved its submission to the APSnet Education Center.