Keyboard accessibility feedback on Tug-of-War PHeT simulation

Jonathan Hung jhung at
Thu Nov 13 19:49:26 UTC 2014

Hi everyone,

Anastasia and I did a quick keyboard accessibility walkthrough of the
latest tug-of-war game in the "Forces and Motion Basics" PHeT simulation,
with the developer "accessibility flag" enabled.

* Link to github version
<> (the version we
* Link to production version on the PHeT website

This is what we discovered. NOTE: we restricted the scope to keyboard
interaction only at this time.

Priority should be given to  giving keyboard access to items that are
currently not keyboard accessible (i.e. reset button etc.). This will at
least make the simulation completely navigable by keyboard.

Once this is done, attention can then be given to tweaking the interaction
to make the keyboard experience more pleasant.

*Some features not **keyboard focusable:*
Some buttons on the interface are mouse-clickable, but not focusable by
- reset simulation button
- audio / mute button
- about item in popped-up menu
- return button

*"Go" button tab order:*
Consider changing the tab order to allow a player to get the sim working as
quickly as possible. Currently the tab order is:

1. blue players, left to right
2. red players, left to right
3. sum of forces checkbox option
4. display values checkbox option
5. go button
6. menu button (lower right corner)

The "Go" button can be moved up to 3rd in the tab order.

*Other interaction notes:*

Activating the menu button makes screen dim and the “about" popup appears,
but you can't dismiss the popup by pressing Space again.

If all 4 players from a team are on the rope, attempting to remove a team
member just subtracts their force from the arrow, but they are visually
still on the rope. It's possible to get all pullers off the rope, but it
requires focusing on other items first and then back on the pullers.

Go button will get focus and can be activated even if no players have been
moved to rope.

Reset (clicking it, since it doesn’t get keyboard focus) doesn't remove all
players from the rope (visual bug only; sum of forces is reset to zero)

Return and circular reset button are ambiguous to someone who has not tried
the simulation.

With keyboard interaction, pullers are placed into predetermined spots on
the rope when activated. Mouse interaction is more flexible allowing the
user to place pullers on any spot. Keyboard users should get the same
freedom to choose where to place their pullers.

Let us know of any comments or questions.


- Jon.




*T:* 416 977 6000 x3951

*F:* 416 977 9844

*E:* jhung at


Inclusive Design Research Centre

205 Richmond Street W, Toronto, ON, M5V 1V3
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