Resizing images can be a pain especially if you don’t have the appropriate hardware and more importantly software like Photoshop. I have found a few free (sometimes limited) tools that resize images quickly, easily, and you are even able to correct colors or add special effects.

Here they are:

Picresize:
http://www.picresize.com/
Pros-extremely easy to use and allows you to resize (shrink only), crop, add effects and even change the type of file. No-account required!
Cons- slow to download resized image if you use the percentages resize. So if you use the manual sizing it works great.

Reshader:
http://reshade.com/online-image-resizer/add-image
Pros- resize both ways, preset sizes to choose from, add effects. No-account required!
Cons- all limitations are exclusive to the free version, limited to only 3 images per day, limited resolution size that you can upload (4000 x 4000).

Pixenate:
http://pixenate.com/
Pros- most options for editing the photo (resize, rotate, brighten, redeye, crop, drawing etc), still fairly easy to use, live preview of changes, upload directly to flickr. No-account required!
Cons-

Photoshop online:
https://www.photoshop.com/
By far the most powerful of all but by far the hardest to use. If you have experience in photo editors or want to get some then this is the one for you. to save any edits you make you also need to have an account.

How can these apps be used in education?

• Resizing photos and image for their course
• Make your file size smaller so its faster
• Add captions to mundane images
• Have students make their file sizes smaller to ease your inbox

Thats what I have now I would like to hear what you have.