Adding code to child nodes

Hi!
I have been able to figure out how to spawn child nodes, but I’m not able to make the child nodes do anything. This is my current code:

:os.cmd('epmd -daemon')
    {:ok, parent} = Node.start(:parent@localhost, :shortnames)
:child.start(:localhost, 'child_1')

Spawning a function in the child node results in an error:

Node.spawn(:child_1@localhost, fn -> IO.puts "test" end)

IO.puts appears as undefined for the child node. How do i load code into child nodes?