arithmetic
background
basic
billboard
board
calculate
calculation
chalk
chalkboard
childhood
class
classroom
college
communication
divide
division
easy
education
elementary
eraser
exam
green
icon
knowledge
learn
lecture
lesson
material
math
mathematical
mathematics
minus
multiply
old
plus
primary
remember
reminder
school
scratch
sign
study
subtraction
sum
symbol
symbolic
teach
teacher
times