[b]* an object (Blue) for the internal jaws to measure width of an object with slider to control width of the object and simple drag action to control position of object.
* an object (Green) for external jaws to measure internal diameter of a cylinder for example with slider to control dimensions of the cylinder.
* checkbox for answer to show the meaning of reading on the main scale and the vernier scale with zero error calculations if any.
* drop down menu of the various common vernier scales for sense making and additional testing out by learners their ideas of how vernier works.
* fine <> control buttons for learners to manipulate the model with single incremental precision
* slider control for fast changes in the vernier measurement
* reset button to bring simulaton back to original (default)
      setting.[/b]