Maybe it's just me, but this doesn't seem to make any sense - you are putting your string into the first element of your array, but nothing into subsequent elements - why not just use a scalar? And what is your splice meant to do?

Then you are creating a new string (just the one) and pushing that into element 0 of another array. Again why not use a scalar?

Are you sure you haven't misunderstood the class assignment? ;)

$scalar="PERLPERBPERCPERD";
$homework = join ' ', $scalar =~ /(.{4})/g;
print $homework;
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