Conditional sentences (1st grade)

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/0cond.htm (zero)

http://www.ego4u.com/en/cram-up/grammar/conditional-sentences/type-1/exercises (1st)

http://www.ego4u.com/en/cram-up/grammar/conditional-sentences/type-2/exercises (2nd)

This video class is really useful!  http://www.engvid.com/zero-and-first-conditionals/