form into (something)
1. To assume or take a particular shape. Come on, kids, form into a line for recess!
2. To cause someone or something to resemble a particular shape. In this usage, a noun or pronoun can be used between "form" and "into." Roger was so bored during dinner that he started forming his peas into a heart.
form (up) into something
[for a group of people] to assume the shape of something. The boys formed up into a jagged line. We'll form into a line.
form someone or something into something
to shape someone or something into something. We formed the people into a line. Kathy formed the clay into a small elephant.