tee is super useful, the problem you have if you where to do:
echo "the user needs to see this" >> some_file
the text redirected to some_file, the user won't see it in the command line. This is where tee comes in:
echo "the user needs to see this" | tee some_file
now the text will be shown in the command prompt, and tee logs in some_file. Now you have both, super useful, maybe it should be included in the course?
note: topic referencing this topic.