Use of could and couldn´t (5th Grade)

Take a little time to practice:
http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-91443.php
http://www.englishexercises.org/makeagame/viewgame.asp?id=8397
http://www.englishpower.eu/es/ep-lecciones-gratis-para-aprender-ingles/nivel-inicial-para-aprender-ingles/modales/el-verbo-modal-can/exercise/54-exercise-2-could-couldnt

Miss Ximena