by reading a three-digit numeral without using the word "and"
321 is three hundred twenty-one, NOT three hundred AND twenty-one.
by reading a given number word (0 to 1000).
by showing a given number as an expression; 300 - 44 or 20 + 236 for 256.
by showing a given number, using manipulatives such as base ten blocks.
by showing a given number in a picture of some kind.
by writing number words for multiples of ten up to 90.
by writing number words for multiples of one hundred up to 900.