It's not a scope problem. The problem is that «Animal::Hog->sound();» comes before «my $sound1 = "knor1";» and «our $sound2 = "knor2";». You're basically inlining a module, but you're not properly emulating «use». To do so, use

BEGIN {
    package Animal::Hog;

    ...

    $INC{'Animal/Hog.pm'} = __FILE__;
}
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In this case, you can avoid doing the last statement. Simply adding «BEGIN» would do the trick.