In my HUMBLE opinion, a written test will work out better with a multiple answer format.
My opinion is the Written test should also be password protected and be backed with an encryption lock so that the answers and the test can be controlled and no CHEAT SHEETS can be easily made or distributed.
I believe that some of the areas of coverage should consist of:
1. Aptitude- Do you know how to measure roof pitch? Do you or do you NOT use 3000 psi and a ZERO degree tip to clean a asphalt shingle roof? etc.
2. Right Equipment- What are the proper ways to couple two pieces of AG hose, what pumps, hoses, what flow rates, tip sizing
3. Fall Protection- What to use and why
4. Chemicals -Descibing what the main chemicals do and how to use them properly and why and in what scenarios
and what CHEMICALS to NOT mix together and why
5. Roll Out and Roll Up- Proper proceedures
6. Landscape and Foliage Protection-
What to protect and Why?
When to tarp and when NOT to?
What not to cover with tarps. Why spray clear water on plants before starting a job. When NOT to and WHY.
7. Runoff- What do do with excess unused chemical. Proper disposal techniques.
8. Licensing- Why be licensed and insured? Why is it important to obtain a business license? The pitfalls of "SHORTCUTS"
9. Basic Safety Equipment- Why use a Fall Protection System? What is a Fall Protection System? Do you have a CPR and First Aid Certification? Why is this important? Do you have the proper footwear? Eye protection. Hearing protection? What type of clothing to wear? What not to wear and why.
10.OSHA Guidelines- What is a MSDS? Why should you carry one for chemicals onboard your rig? Who may ask for them? Why must you comply? Various laws on chemical storage, labeling, handling, etc.
Just like a "real" test in a college or at the Motor Vehicles Division when getting your Drivers license. Lets make this test professional and THE STANDARD by which "OTHERS" will follow.
Better to put in the time now to get it right then bring it to the community "Half Baked" and it be considered a "joke" rather than a well deserved, testing credential that VALIDATES one's abilities, and aptitude to perform the required service of PROFESSIONAL ROOF CLEANING.
Make CERTIFICATION mean something. "If you can't STAND for something, you'll FALL for anything"
Just my .02 cents.