verb
make or become hard or solid.
"the magma slowly solidifies and forms crystals"
Similar:
harden
go hard
set
freeze
ice over/up
gel
thicken
stiffen
congeal
clot
coagulate
curdle
cake
dry
bake
consolidate
ossify
fossilize
petrify
gelatinize
Opposite:
liquefy
melt
thaw
gasify
make stronger; reinforce.
Because camels backs are lumpy
Answer: The time period was from a time ago. At least before they had whiteboards and still when they had to use wooden ovens to keep warm instead of a heater. The chalkboards aren't used anymore and not many teachers refer to children as primary children.
Explanation:
I'd say 3,4, and 5, but an argument can be made for 2. Also Hans Zimmer is an international treasure. Hope this helped.