40s
academic
adult
black
blackboard
board
boy
caucasian
chalk
children
classmate
classroom
concentration
desk
education
equation
explaining
female
formula
geometry
girl
greenboard
high
knowledge
learning
male
man
math
mathematics
mature
men
occupation
people
professor
rear
school
schoolboy
schoolchildren
schoolgirl
schoolwork
side
student
study
teacher
teaching
teenage
teenager
trig
trigonometry
uniform