terminology - What are these extra phrases added to the beginning of sentences called?

I find that my students are using a lot of these phrases at the beginning of their sentences:

• First...


• First of all...


• To begin with...


• All in all...


• The other reason is that...


• Above all...


• At last but not least...


• Taking all the reasons and examples into consideration...


• In a word...

Do these phrases have a common name?

Is there a special term for such phrases when they do not add any meaning to the sentence they are added to?