How to add a watermark to a Google Document:
1. Open your document.
2. Open the "insert" drop-down menu.
3. Select "watermark" from the drop-down menu.
4. Click "select image" to choose an image to use as the watermark on your document. You can upload images, choose from Google Drive or Google Photos, or conduct a Google Images search to apply an image as your watermark.
5. Choose the size of your watermark.
6. The watermark will appear on all pages of your document.
Applications for Education
Applying a watermark to a Google Document could be an easy way to include your school or school district's branding on documents that you plan to print and send to parents. It's also helpful to anyone who is creating materials like lesson plans that they plan to distribute for others to use but want to make sure that credit is given to them. For example, I plan to use the watermark feature on documents that I create for distribution during my webinars and workshops.