Jotflash is a flashcard program for learning visual materials that are drawn or written. For example to learn Japanese characters, it helps to practice mapping from the sound (hiragana) or meaning to the written character (kanji). In this program, you can write on the screen to practice the character. There is an answer button which shows the target character and a clear button for starting over. When you are done, you can press the next button to go to the next item.
The program selects the next test item probabilistically based on how difficult you found the item previously. This is indexed by how often you clicked on the answer button. If you needed to check the answer several times, it shows that that item is difficult. If you want to practice a particular item more, press the answer button more. If you want to stop practicing an item, then do not press the answer button and its probability of being selected will be reduced.
Normally people study characters by writing them over and over, but this is less effective, because you are simply copying the character visually, rather than using the sound/meaning to write the character from memory as you would be in a class test. The random selection procedure also insures that you cannot learn the characters by their position in the study list, which can happen when you write characters based on a fixed list of cues. Also, the probabilistic algorithm insures that difficult characters are repeated, but also that these repetitions are spaced to be more effective.
Although it was designed for learning kanji characters, this program can be used for any topic where visual diagrams are needed, e.g., drawing chemical structures, electrical circuits, biological structures, or human anatomy. Also, these can be used as regular flashcards even when there is no special written component. There is a page for downloading existing lists or for creating your own.