CREATE TABLE "list" ( 
	"LastName" TEXT, 
	"FirstName" TEXT, 
	"Grade" INTEGER, 
	"Classroom" INTEGER,
	PRIMARY KEY(LastName, FirstName)
)

CREATE TABLE "teachers" ( 
	"LastName" TEXT, 
	"FirstName" TEXT, 
	"Classroom" INTEGER,
	PRIMARY KEY(LastName, FirstName)
)
SELECT classroom ,  count(DISTINCT grade) FROM list GROUP BY classroom
For each classroom, show the classroom number and count the number of distinct grades that use the room.