blackboard

board

boy

caucasian

chalk

chalkboard

child

childhood

class

cleaning

contamination

coronavirus

door

dust

education

elementary

explaining

family

hand

horizontal

human

illness

knowledge

learning

lesson

male

man

mask

medical

net

people

pointing

preschool

prevention

pupil

quarantine

respect

school

son

sponge

symbol

teaching

virus

white

wipes

work

young