The Preview application on every Mac is probably one of the most powerful tools you can use, the only problem is many people have no idea how useful it is.
You can use Preview for editing all sorts of image and PDF files, whether you want to crop, resize, or even delete a colour or background, Preview can do it all, without the bother of having to import the image into iPhoto.
A quick Google search for 'Preview Mac' will reveal several sites that do a great job of revealing some of Preview's secrets, here a few:
What is particularly useful is using Preview with your students as a tool for saving and annotating web pages; here's how:
First 'Save' the web page as a PDF, this will vary slightly depending on the browser you use - in Chrome, one way is File > Print > Open PDF in Preview
Then if you open the thumbnail view (View > Thumbnails)
You can delete pages you don't want, and crop pages you do.
Then you can use the Annotate tools to do things like...
- highlight text
- strike-through text
- add shapes, callouts, thought bubbles
And more ...