Where does “classroom” come from?

I need to work through this chain carefully, but I notice there's a problem: the chain provided traces "room" back through Latin "classis" (which means "fleet" or "class"), but "classroom" is a compound of "class" + "room." The chain given doesn't actually support the etymology of "classroom" as a whole—it only traces "room." Additionally, the chain itself appears problematic: Latin "classis" (fleet/class) doesn't derive from Proto-Indo-European *kelh₁-, *rowə-, or *rewh₁- in standard etymological accounts. And the chain jumps around in a non-linear way (going to multiple PIE roots) rather than showing a single descent path. Given the rules state "State only what the chain supports. Do not invent dates, cognates, or intermediate steps," I cannot write an accurate sentence because: 1. The chain doesn't

classroom (English): A room, often in a school, where classes take...

Definitions

  1. A room, often in a school, where classes take...

Ancestry of “classroom”, step by step

classroom traces back through two separate lines of ancestry.

via English class

StepLanguageWordMeaning
1EnglishclassA group, collection, category or set sharing...
2Frenchclasseclass, type, group; "Une classe de conscrits"...
3Italianclasseclass; classroom; style
4Spanishclaselecture; class; kind, sort, type
5Portugueseclasseclass, kind; class; elegance; class
6Germanklassegreat, awesome
7Russianклассclass
8Latinclassisany one of the five divisions into which Servius...
9Proto-Italicklāssis
10Proto-Indo-Europeankelh₁-to call, cry, summon

via English room

StepLanguageWordMeaning
1EnglishroomOpportunity or scope; Space "for" something, or...
2Middle EnglishroumA space or area; A room
3Old Englishrūmroom, space; roomy, spacious, ample, extensive,...
4Proto-West Germanicrūmroomy, spacious; room, open space
5Proto-Germanicrūmazroomy, spacious, open
6Proto-Indo-Europeanrewh₁-free space

Words derived from “classroom

Every word from Proto-Indo-European kelh₁-