How do I flatten the illustrations into the background?
If you are creating educational resources for distribution, either for free or as paid items, you'll need to ensure that the illustrations are secure within the file as per my Terms of Use. The process with vary depending on what software program you are using the create your resource but essentially you need to merge all the layers to create a single image that you insert as a secure background in your file.
Here are some articles from teacher-authors that offer some tips on securing images: