Hello there, @Carol Bridgman.

Let me furnish you with information about class tracking and the project feature  in QuickBooks Online.

QuickBooks class tracking enables you to track specific expenses and income and categorize shared expenses across multiple accounts. You can enter your clients as customers and create a class list to keep track of your income and expenses by department, location, property, project or event. 

First, let's enable your class tracking feature:

1. Go to the Gear icon.
2. Choose Account and Settings.
3. In the navigational bar, click Advanced.
4. Select Categories.
5. Check off Track classes to turn on class tracking.
6. Click Save and then Done.

Now, let's create a class lists:

1. Click the Gear Icon.
2. Select All List.
3. Choose Classes.
4. Click the New button.
5. Enter the name of the Class. 
6. Hit Save.

Once completed, you can now assign each class to a specific item on the estimate, invoice or bill you're creating in QuickBooks. 

On the other hand, you can also utilize the Project feature in QuickBooks Online as mentioned by @Anonymous. This feature allows you to group together all the sales, expenses, time sheets and reports for one project or job. For a more detailed information, you may check out this article: Projects FAQs.  

Please don't hesitate to get back to us here in the Community if you have other questions about class tracking in QuickBooks. I'm always here to help.