500
An implied main idea for this paragraph.
Gone are the odor-free wonderful days of chalk. Now, as students sit before white boards instead of chalkboards, teachers scrawl lessons with dry-erase markers. A teacher’s chalk might, on occasion, accidently screech across the board, whereas the dry-erase marker chirps its every word. The teacher would easily brush chalk dust off hands and clothes; on the other hand, now, the teacher must wash marker stains with soap and water. Chalk had no smell, but dry-erase markers reek of chemical fumes.
What is "Chalk was a better choice than the now more commonly used, dry-erase markers."