Planetizen AICP* Exam Preparation Course
- 90% of students who took Planetizen's AICP Exam Preparation Course in November of 2011 passed the test and became AICP certified.
- The national pass rate for the AICP exam is only 64%.
- Over 1/3rd of all successful AICP exam takers used our course to help them pass.
Planetizen AICP* Exam Preparation Course
Term
January 15 - June 15, 2012
Instructor
Jennifer Evans-Cowley, PhD, AICP
Registration
$159.00
Companion book, Essential Readings in Urban Planning also available
We are now accepting registrations for the January 15 - June 15, 2012 course term.
Are you ready to take the AICP* exam? Planetizen offers a convenient, self-paced online preparation course to help you successfully prepare for the exam. The Planetizen AICP* Exam Preparation Course provides step-by-step, progressive, and interactive instruction that leads you through specific methodologies, lessons, exercises and sample questions.
Join over one thousand other students who have successfully used the Planetizen AICP* Exam Preparation Course to prepare for the American Planning Association's AICP* exam. The Planetizen AICP* Exam Preparation Course has been completely redesigned to align the course with the new computer-based testing format, and now also includes over 10 hours of streaming video.
Updated for the Latest Revision of the Exam
Planetizen's online AICP* Exam Preparation Course has been updated to comprehensively cover everything you'll need to know to study to pass the test. The new version of the course includes expanded coverage of AICP's* Code of Ethics, as well as an in-depth discussion of public participation and social justice issues in planning. This update also includes detailed information on such spatial planning topics as downtown planning, historic district planning and waterfront planning, providing a comprehensive and rounded planning review that will help you get ready for the AICP* Exam.
Features
- Eight course topics, each with a series of 20-30 minute lessons to help you organize your studies
- Three practice exams (170 questions each)
- Pretest evaluation (170 questions) to help you determine your level of readiness
- Ten practice questions for each topic to help you demonstrate mastery of the topic
- Ten hours of streaming video training on nine topics, recorded during the Planetizen/USC AICP workshops held in July, 2009 and 2011.
- Two hours of streaming video training specifically on the AICP code of ethics, by ethics expert, Carol Barrett, FAICP.
- A total of over 700 unique sample questions
- Six discussion forums to interact with other students and course staff, and ask any questions you might have as you prepare for the exam. All questions are answered within three days (but usually faster)
- Over 30 fact-filled lessons introduce a variety of topics, from History, Theory, and Law (Topic 2) to Ethics, Public Interest, and Social Justice (Topic 7)
- Discussion forum posts can be set to be emailed to you, keeping you notified about course activity, even when you're too busy to login
- See who else is online while you are studying
- 100% web-based. You can access the course anywhere you have a web browser and access to the Internet
- Three course staff members available to help you. Course staff includes the course instructor, the course facilitator, a course manager (who handles billing, account setup and administrative matters) and a course technical support specialist
- Hundreds of comments from students who have previously taken the exam
- Access to the course for 30 days after you take the exam in order to post comments and read about the experiences of other test-takers
- Course Instructor
- Course Outline
- Registration Options
- Purchasing Information
- Lesson 1: The Structure of the Exam
- Lesson 2: The Nature of the Exam
- Lesson 3: Commentary from AICP* Candidates
- Lesson 4: Before the Exam
- Lesson 5: During the Exam
- Lesson 6: The AICP* Exam
- Lesson 7: References
- Lesson 8: Other Recommended Study Guides
- Lesson 9: Advice from Past Exam Takers
- Lesson 10: APA Policy Guides
- Video Training: AICP* Exam Overview and Practice Test
- Video Training: How To Study for the Exam
- Pretest Quiz (170 questions)
- How Well Did You Perform The Pretest?
- Lesson 1: Introduction
- Lesson 2: Strategic Planning and Visioning
- Lesson 3: Goal Setting
- Lesson 4: Data Collection
- Lesson 5: Quantitative Analysis (Site Analysis)
- Lesson 6: Quantitative Analysis (Statistics)
- Lesson 7: Quantitative Analysis (Population Estimation)
- Lesson 8: Quantitative Analysis (Economic Analysis)
- Lesson 9: Demographics
- Lesson 10: Information Systems
- Lesson 11: Fiscal Impact Analysis
- Lesson 12: Introduction to Plan Implementation
- Lesson 13: Environmental Impact Analysis
- Lesson 14: Budgeting
- Lesson 15: Project and Program Management
- Video Training: Plan Making
- Video Training: Plan Implementation - Part 1
- Video Training: Plan Implementation - Part 2
- Sample Questions: Plan Making and Implementation
- Lesson 1: Introduction
- Lesson 2: Natural Resources and Environmental Quality
- Lesson 3: Energy
- Lesson 4: Transportation
- Lesson 5: Housing
- Lesson 6: Land Use Regulations (Subdivisions)
- Lesson 7: Land Use Regulations (Zoning)
- Video Training: Functional Areas of Practice
- Sample Questions: Functional Areas of Practice
- Lesson 1: Introduction to Spatial Areas of Planning
- Lesson 2: Planning at Different Scales
- Lesson 3: Corridor Planning
- Lesson 4: Neighborhood Planning
- Lesson 5: Waterfront Planning
- Lesson 6: Historic Districts
- Lesson 7: Downtown Planning
- Video Training: Spatial Areas of Planning
- Sample Questions: Spatial Areas of Planning
- Lesson 1: Introduction to History, Theory, and Law
- Lesson 2: History
- Lesson 3: Theory
- Lesson 4: Law
- Lesson 5: Application of Legal Principles
- Video Training: History and Theory of Planning
- Video Training: Law Review Pt. 1
- Video Training: Law Review, Major Court Cases
- Sample Questions: History, Theory, and Law
- Lesson 1: Introduction to Public Participation and Social Justice
- Lesson 2: Multicultural and Gender Issues
- Lesson 3: Public Participation
- Lesson 4: Negotiation and Coalition Building
- Video Training: Public Participation and Social Justice
- Sample Questions: Public Participation and Social Justice Quiz
- Lesson 1: Ethics Resources
- Lesson 2: Ethics Questions
- Video Training: Planning Ethics with Carol Barrett, Part One
- Video Training: Planning Ethics with Carol Barrett, Part Two
- Video Training: Planning Ethics with Carol Barrett, Part Three
- Video Training: Planning Ethics with Carol Barrett, Part Four
- Video Training: Planning Ethics with Carol Barrett, Part Five
- Video Training: Planning Ethics with Carol Barrett, Part Six
- Sample Questions: AICP Code of Ethics
- Lesson 1: Introduction
- Lesson 2: Examples of Emerging Issues and Trends
- Video Training: Emerging Issues and Trends
- Sample Questions: Emerging Issues And Trends
- Video Training: Questions and Answers
- Video Training: More Questions and Answers
- Sample Exam #1 (**170 Questions)
- Sample Exam #2 (**170 Questions)
- Sample Exam #3 (**170 Questions)
- Course Evaluation
Course Instructor
Jennifer Evans-Cowley, PhD, AICP, has been a member of the American Institute of Certified Planners for the last 13 years and is a Professor of City and Regional Planning at the Austin E. Knowlton School of Architecture at The Ohio State University. Dr. Evans-Cowley regularly teaches courses to prepare candidates to take the AICP* exam and serves as the professional development officer for the Ohio Chapter of the American Planning Association. Prior to becoming a professor she worked as a planner in several cities. Her research regularly appears in planning journals and she is the author of four Planning Advisory Service Reports for the American Planning Association.
Registration
Option 1: Online Course - $159.00
This option includes access to the course January 15 - June 15, 2012, enabling you to study for the May 2012 exam.
Purchase This Option Now
Option 2: Online Course, Plus Essential Readings in Urban Planning - $479.00
This option includes access to the course January 15 - June 15, 2012, plus Essential Readings in Urban Planning which contains many of the readings recommended by the APA. Shipping and handling fee not included.
Purchase This Option Now
What People Are Saying About The Course
"Thank you for creating such a helpful resource. It really made a difference in helping me pass the exam." -- Rosa Y. Ortiz, AICP (Chicago, IL)
"I can't say enough about the Planetizen website, videos and notes. I read and reviewed these multiple times." -- Afsan Hamid, AICP (Bartlett, IL)
"This course really helped me focus my studies and was a great resource overall." -- Erika Martin, AICP (Long Beach, CA)
"I highly recommend this course." -- Omar Masry, AICP (Newbury Park, CA)
"This is my third attempt on the exam, but the first time I've taken this course. Believe me, this course made all the difference. If you have no formal planning training, this course is a condensed form of a masters degree in planning." -- Name Withheld, AICP
"I passed the exam with a score of 62. I took this class after not passing the exam. This class is the reason I passed. I was overwhelmed with the amount of material and with trying to find it on my own. I did not study correctly the first time. This course narrowed the topics and helped me to study the correct subject matter and appropriate depth. Thank you so much!" -- Name Withheld, AICP
"Thanks for this course - it was really, really helpful." -- Patrick Marchman, AICP (Alexandria, VA)
"This was a very helpful course! Thank you!" -- Joshua DeVries, AICP (Kissimmee, FL)
"This course builds confidence and provides a great framework for exam preparation." -- Roberto Zuniga, AICP (Coppell, TX)
"Thank you for such a great course! It was extremely helpful in organizing the insane amount of information!" -- Heidi Jones, AICP (Goleta, CA)
"Thank you. This course was enormously helpful to my study process." -- Molly Wright, AICP (Sacramento, CA)
"This course provided a very strong foundation for my studies." -- Catherine Sckerl, AICP (Austin, TX)
"A million thanks to Jennifer and her wonderful staff for such an amazing product. My advice to potential test takers: enroll in this course as soon as it becomes available. Don't hesitate. This is THE tool that will help you pass the AICP exam." -- Ruben Flores-Marzan, AICP (Manati, PR)
"This course was a instrumental in passing the exam." -- Guilherme Prado, AICP (Atlanta, GA)
"I passed the exam this afternoon with a [removed]! That's where I estimate I was after taking the three Planetizen practice exams. I entered the exam feeling good that I would pass based on the practice exams. The level of difficulty was right where I expected it to be. Thanks for the great study course!" -- Brian Vosburg, AICP (Detroit, MI)
"I would say that [seven different study resources and books] were helpful, but this course was the single most helpful element, especially the practice tests." --Vanessa Goold, AICP (Sunapee, NH)
This course WAS A HUGE HELP!" -- Greg Wagner, AICP (Fergus Falls, NH)
"This course was very helpful. I felt very well-prepared while taking the exam." -- Rebecca Bird, AICP (Champaign, IL)
"I just wanted to thank the entire Planetizen/Urban Insight team for the AICP course. It was very thorough, well-written, and creatively put together. It was money well spent -- I passed with [points to spare]." Mark Meyer, AICP (St. Louis, MO)
"I found this course to be a great resource. I don't think I would have passed without it. I also tried another study resource and found that not to be helpful. Its simply not geared towards the test in the way that this course was." Kevin Kusmick, AICP (Jersey City, NJ)
"Thank you for such a wonderful study aid." Amy Diaz-Barriga, AICP (Evanston, IL)
"This course played a huge role in my preparation for the exam. I took all the practice exams/quizzes multiple times and crossed-checked my weaker areas with other resources... The videos were a great break from reading and provided additional insight to some of the more challenging portions of the exam. Thanks Jennifer, this course was a huge help." -- Robert Caison, AICP (Charleston, NC)
"Thank you for such a great review course, and for answering my questions. I took the exam this morning and passed... I wouldn't have passed if I hadn't enrolled in the Planetizen course and been able to practice so many great questions in the quizzes and the practice exams." -- Lindsay Smart, AICP (Chattanooga, TN)
"This course was incredibly helping in knowing what to study and how to study it." -- Cara Kelly, AICP (Bellbrook, OH)
"This course is a must for those taking the test." -- A. Alexander Flemming, AICP (Havertown, PA)
"Planetizen's AICP preparation course is great. Not have a planning degree and working as a master planning consultant for the military, this course and the video lectures were invaluable." -- Corey Parten, AICP (Marietta, GA)
"The Planetizen AICP Course helped focus my studying, especially since I tend to spend too much time learning stuff in great detail as opposed to learning a little about each topic." -- Keith Leonard, AICP (Grand Junction, CO)
"Thank you, thank you, for putting together such a fantastic course that was so accessible to all of us around the country who may not have been able to attend national conference exam preparation sessions." -- Allison Phillips, AICP (Jemez Springs, NM)
"I studied using Planetizen's AICP course, another study guide, and the Green Book. I would say that they all had their strengths and weaknesses, but this course helped me the most. Being able to watch Jennifer's lectures was great for me because I am need to hear thing and read them. Having never had a single planning class in college, the law, history, and theory stuff was brand new to me. It was a lot to learn. Thanks!" -- Brooke Ferguson, AICP (Greenville, SC)
"I thought that the content of the exam was actually very similar to the types of questions that were in the Planetizen practice exams, and that the exams from this course were very similar to the AICP practice exams in content, but done in a much more user friendly format, with instant feedback available and an answer selection system that much more closely mirrors the actual exam format." -- Hilary Copelan, AICP (Cedar Rapids, OH)
"Thank you Jennifer, and everyone in the course who provided good resources and feedback on the course forums. The Planetizen AICP preparation course was a huge help to me." -- Katie Resnick, AICP (Sandwich, MA)
"The course was a huge help! I wouldn't have passed without it." --Lisa Koch, AICP (Lawrence, KS)
"This course gave a much needed structure and the practice exams give a good idea of the scope and type of questions." -- Krtui Bhati, AICP (Ventnor City, NJ)
"I took the course to help focus my studying, and it helped. I'd recommend it to anyone taking the exam." -- Matthew Bator, AICP (Oceanside, CA)
"I just wanted to let you know that your course was a great investment, and was the only preparation resource I paid for." -- David Campbell, AICP (Lake Orion, MI)
"This course was incredibly helpful with its content and how to organize and what to study." -- Anthony Cataldo, AICP (Baltimore, MD)
"I found this course late in my game - I had already reviewed some [other official materials]. I found this course INVALUABLE. This course is WAY, I repeat, WAY better than the [official materials] which cost twice as much. I loved the lectures! Thanks for making this course available! Recommend it to everyone interested in passing this exam!" -- William Obermann, AICP (Denver, CO)
"This course was very helpful in focusing learning and relearning for the exam. I also enjoyed reading the forums and there was some comfort in knowing that others are suffering along with you in this process!" -- Renee Jordan, AICP (Plano, TX)
I know my job. I studied the APA guidebooks and understood the material. But I don't think I would have passed the test unless i'd taken this class... The course also helped me understand how test questions would be asked. That was important because the question format/style represents a different approach than the typical day-to-day work skills. -- Charles Wise, AICP (Woodstock, NY)
"I definitely attribute this course to helping me prepare. Thanks Jennifer! Thanks Planetizen! I will definitely recommend this course to others!" --Jason Gaines, AICP (Smyrna, GA)
"I want to let you know that your Planetizen videos are amazing! I can't tell you how many times I have reviewed specific definitions and then I watched your video explanation and examples, and I finally get it! They were immensely helpful!" --Susan Lesser (Boca Raton, FL)
"Thank you for this excellent course. This course served as my primary resource, and I definitely would not have passed without it. It was much more comprehensive, supportive, and thorough than [other study] materials. The videos were invaluable, and I loved how I can watch them from the comfort of home." --Lilly Okamura, AICP (Ventura, CA)
"Many thanks to all of the staff who make this program possible. It was my main resource for passing the exam; your practice exams and quizzes are invaluable." --Christopher Park, AICP (Sacramento, CA)
"I believe that the Planetizen course contributed a great deal to my success in passing the AICP exam! I found the structure and content to be very helpful in facilitating my own exam preparation effort! I would highly recommend anyone who is interested in studying for this exam in the future." --Jack Hsu, AICP (Emeryville, CA)
"Initially I was all over the place in studying for this exam, but I found this course extremely helpful in breaking down the study topics. The videos were an excellent resource. Thank you, Jennifer." --Allen Tai, AICP (San Jose, CA)
"The Planetizen course was extremely helpful for all of the history and law questions on the exam... It was also a great review for the project management and citizen participation techniques questions... Thanks for a fantastic course!" --Robyn Welch, AICP (New York, NY)
"This course was very helpful in preparing, especially with a full time job and a 2 year-old at home." --Scott Gustin, AICP (Bristol, Vermont)
"Thank you for making an accessible and affordable course that truly helped me prepare for this test... I was happy to have learned quite a bit during the process. Thank you again!" --Heather Burton, AICP (Los Angeles, CA)
"This course is the best source to get overall knowledge of the test. You could probably just use this course and pass if you study enough." --Rachel Friede, AICP (Vail, CO)
"Thanks, Planetizen! ... I was learning a lot of the detailed planning history/theory and economic development stuff for the first time. This course was so well-organized -- thank you! I went through each of the topics of the course first and took detailed notes, then in the last week before the exam, I watched the videos -- it was a very nice relaxing way to review the material, and I learned some new stuff." -- Teresa Crean, AICP (Newport, RI)
"I really think this course was excellent. There is so much information to get through to prepare for this exam, and this course really helped to get started and provide a basis for organizing my own materials. Also the test exams were very useful. I literally felt it the minute that I started really 'getting' the way to read the questions to find the right answer... Thanks again to Jennifer and the Planetizen Prep Team!" --Erin Miller, AICP (Oakland, CA)
"One of the many benefits of this course is access to feedback from previous test takers and the process and resources they used." --Daniel Coxworth, AICP (Sierra Vista, AZ)
"The practice exams did an excellent job of putting me into the right frame of mind to succeed." --Stan May, AICP (Seattle, WA)
"I want to thank the staff at Planetizen. Your course inspired me to continue studying when I thought that perhaps I should postpone taking the exam. The video training brought clarity to many concepts. Jennifer, you are a great instructor!" -- Diane Bentley, AICP (Oxnard, CA)
"Thanks Jennifer and Planetizen! The online course and sample exams were a huge help and I'd recommend them to anyone considering taking the exam." --Jeffrey Hook, AICP (Atascadero, CA)
"The Planetizen course definitely provided the support and structure required to pass the AICP exam.... Planetizen facilitated in providing the structure and foundation of knowledge needed to think through and solve the questions on the AICP* exam." -- Mary Shearill-Thompson, AICP (Silver Spring, MD)
"...The practice exams were helpful to me in posing situational questions in a format that was similar to many of those on the actual AICP* exam." -- Anthony Fusarelli, AICP (Orange, CA)
"Use this course." --Jayne Yost, AICP (Butler, PA)
"I loved the course and it definitely helped me to pass the AICP* test... I have already recommended your course to many others!" -- Allan Calder, AICP (Boulder, CO)
"Thank you Professor Evans-Cowley and Planetizen - this course was a great asset and I felt connected to others in my situation. I would not have passed or known what to study without your help." -- Richard Miller, AICP (Fort Bragg, CA)
"The Planetizen course does a good job of immersing you in the areas that need to be covered. The course helped me to 'compartmentalize' the topical areas of the exam and that to me was worth the cost of the course alone." --Charles Hall, AICP (Augusta, GA)
"I thought the lectures and the practice exams were really valuable tools... Thanks for a solid review course that I could take as my time allowed." -- Robert Palladino, AICP (Edison, NJ)
"The course is invaluable in summarizing the key essential elements involved and opening the veil into the mystery of the test. I highly recommend to anyone." -- Joseph Scott, AICP (Prescott Valley, AZ)
"Thank you, Professor Evans-Cowley -- the base of my studies was this course. I did not know most of this material prior to the course, since my education was mostly outside of the U.S." -- Lani Ravin, AICP (Burlington, VT)
"I just wanted to extend my thanks for the excellent curriculum and insight into the AICP exam offered on Planetizen's course. I passed the exam ... which I would attribute to lots of well-guided studying." -- Rush Wickes, AICP (Columbus, GA)
"With the online course you're able to study during your lunch hour at work and at home without needing to haul materials back and forth to study." -- Aaron Sorrell, AICP (Dayton, OH)
"If you do not belong to a local study group this course is a must. This course allows busy planners who may not have time to meet regularly to get the benefits of a study group." -- Kimberly Moreland, AICP (Tacoma, WA)
"Planetizen presents an effective strategy for passing the test and he gives you the nuts and bolts needed to do it ... head and shoulders above the APA prep materials." -- Frank V. Giblin, AICP (Washington, D.C.)
"I just wanted to send you a note and thank you for the excellent Planetizen AICP* Exam Preparation Course... I will recommend your course to anyone I meet who contemplates taking the AICP exam in the near future." -- Barry Pearl, AICP, MPA (San Francisco, CA)
"Thank you so much for a great prep course. I would not have passed without it - I am convinced! It provided a great structure to studying for a test that covered so much information." -- Kristine Edens, AICP (Shoreline, WA)
"Thanks to Professor Evans-Cowley and the Planetizen staff for this wonderful AICP prep course. It was very useful indeed!!!" -- Philip Banea, AICP (Las Vegas, NV)
"Your study materials were great! I would not have known where to start or what to study otherwise! The practice exams were very helpful, both for content as well as timing..." -- Susan Rosner, AICP (San Francisco, CA)
"This course was very helpful in preparing for the exam. Thank you, Planetizen." -- Janki Patel, AICP (Middletown, NJ)
"I thought the lectures and the practice exams were really valuable tools. Thanks for a solid review course that I could take as my time allowed." -- Robert Palladino, AICP (Edison, NJ)
"I think the Planetizen course was very, very helpful -- it really got across the correct level of detail needed to answer the questions.... I got both the course readers, which were an excellent resource. They sometimes went into a lot more detail than I think is needed on the exam, but in doing so really drive home the general concepts you need to know." --Anne Morrison (Dhaka, Bangladesh)
"Jennifer is an excellent teacher. Her enthusiasm for the Planning Profession is inspiring." --Taylor Horton, Senior Planner, City of Round Rock, Texas
"The sample questions at the end of each topic helped me gauge how well I was absorbing the lessons. The sample exams at the end of the course gave me the confidence I needed going in to the exam. Thanks Planetizen!" --John W. Baty, AICP
"The on-line videos were the most useful in that they gave a good outline and critical path for my studies." --Fred Kobus
"Very effective review of terminology, law cases and key concepts. The course provides an excellent review of law, theories and key terms. The practice tests were great for measuring progress. Thanks Professor Evans-Cowley!" --Michael Taylor, Senior Planner
Course Outline
While preparing for the AICP* exam, it is simply not possible to study everything. The Planetizen AICP* Exam Preparation Course helps you to focus your limited time and resources by focusing the information most likely to appear on the AICP* exam. The course includes a course introduction and eight topics. Each topic is organized into a series of easy-to-review lessons which can be completed in approximately 20-30 minutes. This lesson-based approach makes it easy for the busy planning professional to fit in a lesson anytime -- during a lunch break, early in the morning before heading off to work, or after putting the kids to bed for the night. Course Introduction This introductory topic includes a variety of orientation materials, including introductions to the course staff, instruction on how to participate in the weekly course chats with students and the scheduled course chat with the instructor. Details are also provided about how to participate in the six discussion forums.
Topic 1: How To Prepare For the AICP* Exam
Registration
Option 1: Online Course - $159.00
This option includes access to the course January 15 - June 15, 2012, enabling you to study for the November exam.
Purchase This Option Now
Option 2: Online Course, Plus Essential Readings in Urban Planning - $479.00
This option includes access to the course January 15 - June 15, 2012, plus Essential Readings in Urban Planning which contains many of the readings recommended by the APA. Shipping and handling fee not included.
Purchase This Option Now
Readers
Essential Readings in Urban Planning
The reader consists of assembled readings that are recommended by the American Planning Association and some which, in our opinion, represent the key knowledge necessary to become a certified planner. This new volume is a comprehensive, 650+ page, bound book that is the definitive collection of essential readings.
Order Now | $349.00 - Printed Edition
Order Now | $479.00 - Printed Edition and Planetizen's online AICP* Exam Preparation Course
Course Account Activation
Your course account will be activated within 1 business day of the time you sign up (Usually within 4 hours if you sign up Monday - Friday, 9am - 4pm Pacific). Questions? Please email us at courses@planetizen.com
Course Registration Policies
- November Exam: Course registration for the November exam opens on May 15, and your account will become active on July 15. You will have access to the course through December 15.
- May Exam: Course registration for the May exam opens on December 15, and your account will become active on January 15. You will have access to the course through June 15.
- At this time we do not offer discounted extensions on the course for the next session. For example, if you register for the online course in March, you will only have access through June 15, and will have to re-register (and pay the course fee) to have access until December 15.
Purchasing Information
To purchase this course, please add it to your shopping cart. Please note that you must be a registered Planetizen user to purchase this course. If you are not a registered user, please take a few seconds and register for free.
* AICP is a registered trademark of the American Planning Association (APA) and the APA's Institute. Neither APA nor AICP are affiliated with Planetizen or this website.
** These are practice questions. They are not real exam questions.














