echo outputs -e parameter in bash scripts. How can I prevent this?

I've read the man pages on echo, and it tells me that the -e parameter will allow an escaped character, such as an escaped n for newline, to have its special meaning. When I type the command

$ echo -e 'foo\nbar'

into an interactive bash shell, I get the expected output:

foo
bar

But when I use this same command (i've tried this command character for character as a test case) I get the following output:

-e foo
 bar

It's as if echo is interpretting the -e as a parameter (because the newline still shows up) yet also it interprets the -e as a string to echo. What's going on here? How can I prevent the -e showing up?