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# PhET Faraday's Law Keyboard Interaction Sketch

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Version 8

## V2.0 (November 17, 2017)

The following is a sketch depicting a possible keyboard interaction for the Faraday's Law simulation (link to Faraday's Law Simulation at PhET). Understanding speed of magnet movement as it relates to flux is an important learning outcome, and this sketch aims to minimize the dexterity / motor function required to successfully gain the learning outcomes.

In the current simulation, the speed of which the magnet moves is directly correlated to the user's physical ability to manipulate the input device. This requires significant dexterity and motor function to accomplish.

In this design sketch, once the user as chosen a direction, the magnet will move in that direction on its own (continuously) like an object floating through space. The user can then choose to increase or decrease the magnet's movement speed (like a throttle), stop, or immediately reverse direction. By allowing the magnet to move on its own, this enables the user to focus on direction and speed without requiring significant motor control or dexterity.

NOTE: Text descriptions of images currently being updated.

Image 1 above: The initial screen for Faraday's law.

Image 2 above: Keyboard focus placed on the magnet.

Image 3 above: Enter is pressed and the user can begin to move the magnet in a direction they choose.

Image 4 above: User has pressed the left arrow key once, and the magnet begins creeping to the left by itself. A single arrow appears in the direction the magnet is moving that indicates it direction and speed.

Image 5 above: User has pressed the left arrow again, and the magnet increases its speed. Two arrows now appear in the direction the magnet is moving to indicate its direction and moderate speed.

Image 6 above: User has pressed the left arrow again, and the magnet is now moving at its maximum speed. Three arrows now appear in the direction the magnet is moving to indicate its direction and maximum speed.

Image 7 above: The user can stop the movement of the magnet any time by pressing ESC, Enter, or any direction key other than the direction they are moving in. The intention is to make it easy to stop movement and give control to the user.

Image 8 above: The user has tapped the right arrow key three times, so the magnet is now moving right at a fast speed by itself.

Image 9 above: The user can reverse the direction any time by pressing the spacebar. This way the student can experiment with speed and movement easily with the spacebar (easy to press) and a few taps of the arrow keys.

Image 10 above: To summarize, the arrow keys control the direction of travel. Once the magnet begins to move, it will continue to do so on its own. It can increase its speed with subsequent presses of the arrow key, switch directions, or stop.

### Possible Design issues

• The "Wild Ride" phenomenon
• How many steps in the throttle?
• Instead of stopping the magnet if a different direction key is pressed, what if the magnet continued moving in the new direction at the same speed?
• What would it be like to have two modes for keyboard interaction: standard cursor control style of interaction, and this "throttle" control scheme?

### Evolving Design Idea

Idea is to have a control scheme inspired by 80's video games like Snake and Asteroids.

Controlling Movement and Direction:

• Movement and speed is controlled by the direction keys.
• Once a direction key is pressed, it will continue to move on its own in that direction.
• Direction can be changed at any time by pressing any of the other direction keys
• Changing directions does not change its speed - it continues at the speed it was traveling at.

Controlling Speed:

• Speed is controlled by dedicated keys like CTRL and ALT to increase and decrease, or 1 - 2 - 3 to change speeds to slow, moderate, and fast.
• Stop is controlled by space bar (or some other key)

Unlike the v2.0 sketch above, this evolving design idea uses the direction keys to control just the direction - making it simpler to understand and control. Speed is mapped to another set of keys making it easier to just focus on movement once you have a speed you like.

## V1.0

Image 1 Above: Initial view

Image 2 Above: User has pressed tab and focus is moved to the magnet.

Image 3 Above: User has pressed Enter, and the magnet is now able to be moved using keyboard.

Image 4 Above: User is in a move state and is also pressing a modifier key, the magnet moves in larger steps. The arrows on the magnet change to visually indicate the change.

Image 5 Above: User is holding a different modifier key, the magnet moves in smaller steps. The arrows on the magnet change to visually indicate this change.

Image 6 Above: Describes a possible issue with keyboard interaction and speed of moving the magnet.

"

Current is related to the speed of magnet movement.

Faster the magnet moves, the greater the current.

Slower the magnet moves, the smaller the current.

Problem:

In this scenario to the left, it will take a keyboard user 4 keystrokes to move to the other side of the coil (as indicated by the green dots).

If the user has sufficient motor acuity, they can move the magnet quickly by holding down the modifier and repeated tapping of keys.

If the user does not have sufficient motor acuity, it will be difficult"

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