Icons are symbols, visually representative signs. Typically they are static, meaning they are the same in every context. This has great benefits: seeing the same symbol in a variety of places means that it communicates an idea extremely efficiently. There is a universality to static icons. 

Static
consistent
predictable

dynamICONs are dynamic. While still benefiting from the consistency of static icons, they can change for different environments. For example the bar dynamICON shows student progress—teachers can "scribble" more and more as a student completes more work.

Dynamic
adaptable
update-able

I want to help students...

• collect ideas – try bullets

• complete next steps – try boxes

• distinguish amounts of writing – try brackets

• make a good enough choice – try rays

• know when to expect something – try a timeline

• progress in their work – try a bar

• resolve a conflict – try a barbell

I have a student who...

• can't think of ideas to write about – try bullets

• forgets what to do next – try boxes

• needs steps broken down – try boxes

• has a hard time starting work – try boxes or a bar

• has time management difficulties – try a timeline

• likes to write parts of a sentence or paragraph in a different order – try brackets

• has a hard time waiting – try a timeline

• doesn't know how much to write – try brackets

• gets overwhelmed with work – try a bar

• hesitates when making an offered choice – try rays

• gets stuck one one solution – try rays or a barbell