In class, we are practising using modals (e.g., would, could, can) for making polite requests. Here are some online practice activities for you to try at home.
Read the sentences, and choose the best words for the blanks:
http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/330-modals-polite1.htm
Quiz yourself with the correct form and structure of can, could, and would:
http://www.learnenglish-online.com/grammar/modals/tests/modalrequests.html
http://www.learnenglish-online.com/grammar/modals/tests/modalrequests2.html