Tux Paint is meant to be a simple drawing program for young children. It is not meant as a general-purpose drawing tool. It IS meant to be fun and easy to use. Sound effects and a cartoon character help let the user know what’s going on, and keeps them entertained.
Tux Paint is extensible. Brushes and “rubber stamp” shapes can be dropped in and pulled out. For example, a teacher can drop in a collection of animal shapes and ask their students to draw an ecosystem. Each shape can have a sound which is played, and textual facts which are displayed, when the child selects the shape.
There is no direct access to the computer’s underlying intricacies. The current image is kept when the program quits, and reappears when it is restarted. Saving images requires no need to create filenames or use the keyboard. Opening an image is done by selecting it from a collection of thumbnails.
Tux Paint is available from Ubuntu official repository, you can use this apt-get command to install it:
sudo apt-get install tuxpaint
Or, just search and install Tux Paint in Ubuntu Software Center.
After installation, you can find Tux Paint in Applications -> Education menu.