Count the pencils.
5 pencils.
Count the backpacks.
7 backpacks.
What's missing?
PEN
Count the rulers.
6 rulers.
Count the erasers.
7 erasers.
Count the pens.
5 pens.
What's missing?
BACKPACK
What's missing?
CRAYON
What's missing?
RULER
Count the crayons.
10 crayons
What's missing?
PENCIL
What's missing?
ERASER