PhET Energy Skate Park - Text Descriptions

This document contains explorations for text descriptions of track shapes for Energy Skate Park.

Observations

• For simple track shapes, descriptions typically begin at the track's "beginning"
• For more complex track shapes, descriptions strategies varied:
  • orderly - describing from left to right (or right to left).
  • general to specific - describe the general shape first before describing the specifics left to right
• Most descriptions were relative to the left or the skater. One user used absolute terms using units and degrees
• Some people incorporated the red nodes into descriptions.

Some Issues to Consider

• The "beginning" is relative. Is it left, right side? Closest to the skater? Will need to set description relative to a fixed location.
  • Suggestion, start at left-most point and start description from there.
  • If start and end positions are in the same vertical space, then the top most is where the description starts
  • If the start and end positions are the same point, then choose the point which goes left and/or upward first
• Feature-based descriptions
  • What are the useful things to describe?

Programmatic Generation of Text Descriptions Based on Slope

Idea: Use some known heuristics of slopes to generate descriptions.

• If the slope is > 1 or < -1, then it is "steep"
• If the slope is < 1 or > -1, then it is "gentle"
• If the slope is 0, then it is a flat horizontal line
• If the slope is near 0, then it is almost a flat horizontal line
• If the slope is NaN or very close to the Rise value, then the slope is vertical or nearly vertical
• If X values repeat themselves, then the track is going back on itself horizontally
• If Y values repeat themselves, then the track is going back on itself vertically (possibly a "hill")
• If both X and Y values repeat themselves, then the track is doing a loop

Potential descriptive text read out by screen reader: “Track has a gentle slope up, then a steeper slope up. Followed by a steep slope down and then another steep slope down. There is a loop, then a steep slope up. Finally there is a plateau.”

Programmatic Generation of Text Descriptions Based on "Node-to-Node"

A player has created a complex track like the following screen snap of a multi sloped track that includes steep slopes, gentle slopes, sharp angles and a loop:

The track can be described node-to-node, so the user gets a general idea of the shape.

A limitation of this form of description is that it does not convey the shape of the track as a whole. Nor does it describe qualities like tracks overlapping one another, or appearing stacked. However, such descriptions may not be important to the overall learning.

Example Tracks