Modal Verbs
shall:Shall + main verb form and indicate future time an intention or action will happen in the future. This modal verb didn't use in the american english.
Link:http://www.englishpage.com/modals/shall.html
must:"Must" is most commonly used to express certainty. It can also be used to express necessity or strong recommendation, although native speakers prefer the more flexible form "have to."
Link:http://www.englishpage.com/modals/must.html
may:"May" is most commonly used to express possibility. It can also be used to give or request permission, although this usage is becoming less common.
Link:http://www.englishpage.com/modals/may.html
can:is one of the most commonly used modal verbs in English.
could: is used to express possibility or past ability as well as to make suggestions and requests.
Link:http://www.englishpage.com/modals/can.html
Link:http://www.englishpage.com/modals/could.html
Should : is an auxiliary verb, a modal auxiliary verb...
Link: http://www.englishclub.com/grammar/verbs-modal-should.htm
Must: We often use must to say that something is essential or necessary..
Link:http://www.englishclub.com/grammar/verbs-modals-have-to-must-not-2.htm
Be able to: Although we look at be able to here, it is not a modal verb. It is simply the verb be plus an adjective (able) followed by the infinitive. We look at be able to here because we sometimes use it instead of can and could...
Link:http://www.englishclub.com/grammar/verbs-modals_can_3.htm
Need to /Needn`t: need (MUST HAVE) verb to have to have (something) or to want (something) very much.
Link:http://www.britishcouncil.org/learnenglish-central-grammar-need.htm
Don`t have to to : is used when there is no obligation to do something...
Link:http://www.bbc.co.uk/worldservice/learningenglish/radio/specials/1425_gramchallenge18

Games:
- http://www.englishexercises.org/makeagame/viewgame.asp?id=2786http://www.englishexercises.org/makeagame/viewgame.asp?id=3023
- http://www.educaplay.com/es/recursoseducativos/620458/modal_verbs.htm
- http://www.educaplay.com/es/recursoseducativos/835060/modal_verbs_use.htm
- http://www.wordsearchfun.com/130423_English_Modals_wordsearch.html
- http://www.flo-joe.co.uk/fce/students/strategy/openclze/modals.htm
- http://www.educaplay.com/es/recursoseducativos/667230/modal_verbs_.htmhttp://www.englishexercises.org/makeagame/viewgame.asp?id=5437
http://www.e-grammar.org/modal-verbs-can-may-must/test3-exercise3/http://www.englishexercises.org/makeagame/viewgame.asp?id=9207