diff --git a/lib/elixir/lib/supervisor.ex b/lib/elixir/lib/supervisor.ex
index 76e8b83f069..6829ee90c21 100644
--- a/lib/elixir/lib/supervisor.ex
+++ b/lib/elixir/lib/supervisor.ex
@@ -990,6 +990,12 @@ defmodule Supervisor do
   value, or if it fails, the child specification is discarded and this function
   returns `{:error, error}` where `error` is a term containing information about
   the error and child specification.
+
+  > #### Order Among Children {: .tip}
+  >
+  > The child specification is **appended** to the children of `supervisor`.
+  > This guarantees that semantics of things such as the `:rest_for_one` strategy
+  > are preserved correctly.
   """
   @spec start_child(
           supervisor,