Answer: hoponpop

AnswerCrossword Clue
HOPONPOPBook with the words "Fish in a tree. How can that be?"
HOPONPOPDr. Seuss book
HOPONPOPDr. Seuss classic
HOPONPOPDr. Seuss title
HOPONPOP"Red Ned Ted and Ed in bed"
HOPONPOPBook whose last line is "Ask me tomorrow but not today"
HOPONPOPBook with the line "My father can read big words, too. - Like Constantinople and Timbuktu"
HOPONPOPClassic Dr. Seuss book
HOPONPOPDr. Seuss book that introduces phonics