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Questions

  • Better word than "jump"?
    • "Slide"?
    • What if instead "Use the W A S D keys to position magnet. Use number keys 1, 2, 3 to move magnet."?
      • WASD "Move" → WASD "Position"
      • 123 "Jump" → 123 "Move"
  • Is there a keyboard help hotkey?
  • Should there be some sort of text or audible indication that the magnet is in "the zone" (i.e. able to pass through coil if they move left or right)?
    • User testing may reveal answers to this.
  • Can we change label "Field lines" to "Magnetic field"?
    • the word "lines" has little relevance to a non-sighted user
    • also "magnetic field" is more accurate and more insightful in text descriptions.
  • Implementation detail: Use a Meter element for the lightbulb?
  • Need to work through Entering and Exiting the coil
    • What if the user is moving vertically and hears "Entering 4 loop coil" - that would be confusing.
    • Is there a definitive "enter" and "exit"? The perspective of the graphic can make it confusing
  • Is there a Control Panel? What would it be?

Text Descriptions and Alerts

The above diagram shows the Faraday's Law sim with text alerts and text descriptions overlaid. Events can trigger text alerts (aka. Aria-live region updates in the PDOM) and text description updates (sections of text within the PDOM).

Example PDOM

An example of a possible PDOM (alerts, descriptions, and controls) can be seen here: PhET Faraday's Law Simulation - PDOM Sketch

Keyboard Access

Magnet can be moved 2 ways: by moving by steps, and jumping.

The word "jump":

  • is a friendly term
  • not technically correct.
  • approximately describes the motion
  • conceptually distinct from the other magnet movement term "Moving"
  • "jump" is already used in BASE but for a different kind of action."
    • Jump" in BASE = more like a teleport
    • "Jump" in Faraday = more like a slide

Moving by steps

  1. Press Tab to focus the magnet.
  2. WASD direction indicators appear.
  3. Pressing a direction will move magnet one step.
  4. Modifier CTRL will make the magnet move a larger step.
  5. Modifier Shift will make the magnet move a smaller step.

WASD Indicator behaviour

Like BASE, WASD indicators disappear once the magnet moves. WASD indicators reappear if focus is moved off magnet and back again.


Moving by jumping


  1. Tab to focus the magnet.
  2. User can press a jump key 1, 2, or 3 to jump the magnet to the other side of the play area.
    1. 1 = slow jump
    2. 2 = normal speed jump
    3. 3 = quick speed jump.
  3. While a jump key is depressed and while the magnet is jumping
    1. a faded placeholder image of the magnet is shown where the magnet will eventually stop.
    2. an arrow indicates the speed and direction of the movement. 1 arrow = slow jump, 2 arrows = normal jump, 3 arrows = quick jump.
  4. If focus is moved off the magnet in the middle of a jump, the magnet will stop and a magnet stop alert is fired.

Edge case - jumping with bumping into a coil


Same as a normal jump except the faded placeholder appears next to the coil (where it will stop).

Edge case - Coil Obstruction


A special case where the magnet is starting from a position where it is blocked from jumping or stepping by the coil. A number of things will happen:

  • Magnet stays where it is - there is no movement of the magnet in the direction of the coil.
  • A "coil bump alert" will be fired.
  • Audio feedback will be heard (the coil bump earcon).

Example Interactions

For this example, it helps to have the sim with keyboard access open in another window:

https://bayes.colorado.edu/dev/html/faradays-law/1.4.0-keyboard_jump.3/phet/faradays-law_en_phet.html?accessibility

Part 1: WASD movement

  1. Loads sim.
  2. Presses tab
    • keyboard focus appears on magnet
    • WASD indicators appear
    • magnet focus alert triggered: "Magnet at middle-right of the Play Area. Use the W A S D keys to move magnet. Use number keys 1, 2, 3 to jump magnet."
  3. W tapped 1 time
    • WASD indicators disappear
    • Movement Alert with Step Size / Direction Change: "Left 1 regular step."
    • keyboard focus remains on magnet
  4. W tapped 1 time:
    • Movement Alert: "Left"
    • Sonification of lightbulb is heard.
    • keyboard focus remains on magnet
  5. W tapped 1 time:
    • Movement Alert: "Left."
    • Location Alert: "At centre of play area."
    • Coil proximity alert: "Very close to 4 loop coil."
    • Text description update: magnet description - location change and coil proximity.
    • Sonification of lightbulb is heard.
    • keyboard focus remains on magnet
  6. S tapped 1 time:
    • Movement Alert: "Down 1 regular step."
    • Sonification of lightbulb is heard.
    • keyboard focus remains on magnet
  7. S tapped 1 time:
    • Movement Alert: "Down."
    • Coil proximity alert: "In 4 loop coil." (this is not reported as a Coil Enter / Exit Alert occurs)
    • Coil Enter alert: "Entering 4 loop coil."
      • (question) This is somewhat awkward. The user has pressed down and gets an "Entering" alert. This would imply that the Exit is somewhere below, but it is in fact to the left.
    • Text description update: magnet description - coil proximity.
    • Sonification of lightbulb is heard.
    • keyboard focus remains on magnet

Part 2: Keyboard jump

Continuing from the sequence in Part 1 above.

  1. Tab is pressed until focus is on the Field Lines checkbox
    • Screen reader announces focus on Field lines checkbox
  2. Field lines checkbox checked
    • Field lines appear on the magnet
    • Magnetic field alert: "Showing magnetic field lines. Strong magnetic field passing through 4 loop coil".
    • Text description update: Circuit description updated to include magnetic field.
    • Enable magnetic field line earcon is heard.
  3. Tab is pressed repeatedly until focus is on the magnet
    • keyboard focus appears on magnet
    • WASD indicators appear
    • magnet focus alert triggered: "Magnet at center of the Play Area. Use the W A S D keys to move magnet. Use number keys 1, 2, 3 to jump magnet."
  4. Slow jump key pressed (not released)
    • Magnet placeholder appears on other side of play area.
    • Single left pointing arrow indicator appears next to magnet
    • focus remains on magnet
  5. Slow jump key released
    • Jump start alert: "Jumping magnet slowly to left side of play area. Press Space to stop jump."
    • Magnet placeholder remains on other side of play area.
    • Single left pointing arrow indicator appears next to magnet
    • focus remains on magnet
  6. Magnet slow jumping in progress passing through 4-loop coil
    • Sonification of lightbulb is heard.
    • keyboard focus remains on magnet.
  7. Magnet slow jumping in progress exiting 4-loop coil
    1. Coil proximity alert with field lines: "Very close to 4-loop coil and very strong magnetic field passing through."
    2. Sonification of lightbulb is heard.
    3. keyboard focus remains on magnet.
    4. TODO: Finish working through this interaction

Appendix

Description Regions

Figure 2: An example of the different proximity descriptors for the magnet as it moves from one region into another.

Figure 3: Play area location descriptors.

Figure 4: Magnetic field intensity descriptors.



Other



**Remarks:**

* Movement, coil proximity and location change alerts may be sufficient to give sense of progress in most cases.

* For blank steps, it may be appropriate to periodically give a location or coil proximity change event, or a movement alert.

* For quick moments, multiple alerts may occur within a small window. It may be necessary to prioritize alerts to report.

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