Batch Invoicing

That's right, emrosenow. You can create and import a CSV file to accomplish this task seamlessly. 

With the Batch invoicing feature in QBO Advanced, you can manually enter up to 30 invoices at once. Since you want to bill 200 school customers, you can use the Import CSV  option to streamline the process. 

Take note that you can only upload up to 150 transactions at a time. Hence why, you'll need to make two separate files. Here's how to import your invoice:

1. Select + New.
2. Select Batch transactions.
3. Click the Import CSV.
4. A window will pop up and from there on, click the download this sample CSV, to ensure that you're following the proper format. 
5. Hit Browse and select the data you've saved.
6. After that, click Next.
7. Once the data is in QBO, choose Save and send.

Moreover, you can visit this article if you learn how to split estimates into as many invoices as you need. Set up and send progress invoices in QuickBooks Online.

If you have further questions about batch invoicing, you can always get back to this post by leaving a reply below. I'm always here to lend a hand.

@emrosenow 

If you are using QB Payment, you can prepare Inoivce data with the following template

then use an importer tool to proceed.

https://get.transactionpro.com/qbo