An Unexpected Source of Inquiry-Based Lab Practicals


Each spring my Local Section of The American Chemical Society (ACS) hosts a rigorous two part exam as part of the selection process for the The International Chemistry Olympiad (IChO)  IChO is an annual international competition for the world’s top chemistry students. Each year, nations from all over the world will send teams of four to compete for top honors. The ACS sponsors the Olympiad program and helps select and train students for the competition which is held in a different participating country each July. As part of the selection process, the ACS administers the National Olympiad Exam to more than 1,000 students. Twenty of the top scoring students are selected to attend the two-week Olympiad Study Camp held in June at the Air Force Academy in Colorado.  

When my students ask how they can prepare for the local competition I direct them to the website of released past exams and tell them to download and practice answering the questions. Each national exam is separated into three parts. Part I is a multiple choice test consisting of 60 multiple choice questions and covers a wide range of chemistry topics, and Part II is an eight question free response test covering theories and models. Parts I and II can be downloaded and practiced at home. Part III, on the other hand, is a lab practical. This is the part of the exam that is difficult for students to prepare for on their own. It is also the part of the exam that I have used to create some of the most engaging and fun lab challenges to use in my classroom. They provide authentic learning experiences for all my students, but also help those taking the exam prepare for the lab portion.

The lab practicals on the exams are presented as problems. No procedure is given. Students must use their chemistry knowledge and lab experience to devise a plan and solve the problem. I like this format as it integrated nicely with the Modeling InstructionalTM methods I use in my class. The best part is that the released exams come with lists of materials and equipment, helpful hints to the proctors, and solutions! My students respond well to the format.  They approach each activity like a personal challenge. They brainstorm and bounce ideas off each other. They try different things and report back to each other - collaboratively trying to improve the protocols they design.  

I plan on adapting and incorporating more of these challenges in both my first year and AP courses next year.  

When logged in, registered members of ChemEd X can access the student and teacher files of the Density Challenge that I adapted from Part III of the 2001 exam at the bottom of the post.




Time required: 

45 minutes

  • water and isopropyl alcohol solutions in labeled beakers

  • 2 10 mL graduated cylinders

  • 2 plastic pipettes

  • 4 test tubes large enough for your plastic object to fit inside

  • a bottle of distilled water

  • plastic object (recommended: a drywall wall anchor)


Students will create a procedure to solve the given problem.


This lab calls for 70% (not 91% or 99%) isopropyl alcohol which is sold as “rubbing alcohol” in most stores or pharmacies. You can use the cheapest brand available as long as there are no dyes, perfumes or additivies. Make sure the plastic sample you have chosen will fit in the test tubes and that the sample will float in water and sink in the alcohol. Students should wear lab goggles.  

Lucy Pryde Eubanks, Clemson University, Clemson, SC Chair Robert Becker, Kirkwood High School, Kirkwood, MO Craig W. Bowen, US Naval Academy, Annapolis, MD Nancy Devino, ScienceMedia Inc., San Diego, CA Sheldon L. Knoespel, Michigan State University, East Lansing, MI Steve Lantos, Brookline High School, Brookline, MA Jim Schmitt, Eau Claire North High School, Eau Claire, WI Robert G. Silberman, SUNY-Cortland, NY Christie B. Summerlin, University of Alabama-Birmingham, Birmingham, AL