As part of a demo course in Open edX, I designed the interactions and layout for a simple drag and drop activity. These designs were coded and implemented with the help of one developer, who translated the designs very accurately into a live product.
The final product was very accurate to the assets that were handed off in the development phase. The following are screens from the original photoshop document, which may show a few differences from the live activity.
When using the practice mode, the activity will notify the student that he or she has placed an answer in the wrong bucket.
When using assessment mode, hints are available to use. Hint function generates a solid stroke around one answer and its correct bucket.