Thank you to Salesforce for offering this terrific training opportunity taught by @Fred Zingeser.  Completed about 1/2 the recommended Trailmix before training. 

https://trailhead.salesforce.com/en/users/00550000006yDdKAAU/trailmixes/prepare-for-your-salesforce-platform-app-builder-credential

Looking forward to taking the Platform App Builder certification test in a couple of weeks.