Standardize the wording around ' the shaded area' in the fractions lessons

[adhiamboperes]

Is your feature request related to a problem? Please describe.
I found out through sampling with random people that when asked to give the fraction represented by the shaded area, there was confusion about it referring to the darker parts, or the part with the overlay.

Describe the solution you'd like
Some of the lessons ask for 'the fraction represented by the darker part' which is pretty clear, and I suggest we standardize all references to the shaded area as either the darker area, the darker shade or an equivalent wording.

Describe alternatives you've considered

• Using consistent wording throughout the lessons.
• Using wording that eliminate ambiguity about what the shaded area ctually is.
• Adding a glossary of terms
• Adding parentheses to explain what is needed, e.g. What is the fraction of the shaded(darker) area of the cake?

Additional context
A screenshot of the lesson in question:

[BenHenning]

Thanks @adhiamboperes! Routing this over to the lessons team to triage.