Table 1.

Problem-Solving Strategies, Descriptions, and Examples from Speech and Gesture

Strategy Name	Description	Speech Example	Gesture Example
Irrelevant Strategies
Changed 2D Representation	By changing the length of the bonds between atoms or altering the angle between two bonds, they have created a stereoisomer.	“I made the bonds between the carbon and the hydrogen shorter.”	Pinch two fingers together over the C and H.
No Changes Possible	Regardless of how they change the molecule it can always be rotated back to the original form and thus cannot create a stereoisomer. Or, due to the laws of chemistry no changes are allowed to be made.	“Anyway I drew it, it would still be superimposable on the original molecule”	Point or sweep to every substituent and produce no other gestures.
Ignore Z Dimension	Indicate having changed the location of two substituents by altering their spatial relation on the 2-dimensional X-Y plane of the drawing in such a way that represents no 3-dimensional changes	“Originally the hydrogen was to the bottom left of the carbon, now it’s to the bottom right. And the bromine was on the right, now it’s on the left.”	V-hand shape, pointing to each of the two substituents on the Z-axis, typically wiggling back and forth.
Irrelevant Switch	Participants indicate that rotating two or more substituents that are NOT attached to the stereocenter will produce a stereoisomer.	“I rotated these two CH3s all around this carbon so now it is different.”	Point to a substituent that is not attached to stereocenter, and then sweeps away from the board.
Irrelevant Rotate	Participants indicate that rotating two or more substituents that are NOT attached to the stereocenter will produce a stereoisomer.	“I rotated these two CH3s all around this carbon so now it is different.”	Lift up one hand with fingers pointed upward and twist the hand either clockwise or counter-clockwise. The movement is produced in front of a substituent not attached to a stereocenter.
Relevant Strategies
Relevant Switch	Participants indicate that no matter how their drawn molecule is rotated, it cannot be superimposed on the original molecule. For items that do not have a stereoisomer, rotating the drawn molecule will return the arrangement to its original form and thus it can be superimposed.	“Because regardless of how you rotate the molecule, the parts of this one are not going to line up with the parts of the original one.”	Point with a V-shaped hand to two substituents attached to a stereocenter and flip hand.
Relevant Rotate	Participants indicate that no matter how their drawn molecule is rotated, it cannot be superimposed on the original molecule. For items that do not have a stereoisomer, rotating the drawn molecule will return the arrangement to its original form and thus it can be superimposed.	“Because regardless of how you rotate the molecule, the parts of this one are not going to line up with the parts of the original one.”	Lift up one hand with fingers pointed upward (or both hands) and twist the hand(s) either clockwise or counter-clockwise. The movement is produced in front of the entire molecule or stereocenter.
Mirror Image	Participants indicate that by creating the original molecule’s mirror image they have created a stereoisomer.	“If you reflect the molecule over a mirror plane then you couldn’t match it up with the original.”	Place one hand over one drawing and then flip hand from palm down to palm up over the top of the original molecule
Check Non-Manipulated Substituents	Indicate that a molecule manipulated by either Mirror Image (Lv. 3) or Relevant Switch & Relevant Rotation (Lv. 2) must be compared to the original to check superimposability. Typically participants checked manipulated substituents against their original orientations, then checked the two non-manipulated substituents’ locations to their original orientations	“When you change which one of these two groups are going into the board and which one is coming out of the board, no matter how you rotate the molecule, it won’t be the same. So I rotate this around, these will be back in their original spots, but the two things I didn’t change are now in different spots.”	Point to one or both of the unchanged substituents attached to the stereocenter.