Use of have to, has to amd had to (6th Grade)

Take some time to practice:
http://www.englisch-hilfen.de/en/exercises/tenses/have.htm
http://www.englishexercises.org/makeagame/viewgame.asp?id=8969
http://oudwww.bonhoeffer.nl/engels/2eklas/unit1/wb17.html

Miss Ximena