PicPick

PicPick is a free software that enables you to capture images from your screen. It is also a userfriendly editor of images, similar to other popular editors such as gimp or photoshop, but lighter. It takes less than 6 MB from your hard disk.

It is very useful for teachers who need to show their students how to use software or online resources, as it can capture screenshots and allows you to write instructions, highlight areas and draw arrows indicating where to click or write.