Curriculum and Books › What Do You Hear When Cows Sing? And Other Silly Riddles by Marco and Giulio Maestro Image 1 of 1 What Do You Hear When Cows Sing? And Other Silly Riddles by Marco and Giulio Maestro $1.99 Only 1 available Gently used Add To Cart Added! Gently used Reviews Reviewer Name Review Date Star Rating Description Posted on Etsy Product Show More You Might Also Like Quick View Trace Shapes $1.99 Only 1 available Quick View Mastering The Basic Math Facts in Addition and Subtraction $3.99 Only 1 available Quick View Mathtacular Dvd and Answer key $3.99 Only 1 available Quick View Phonics & English Third Edition BJU Press Teachers Edition Part 1 & 2 $44.99 Only 2 available Quick View Math in Focus Singapore Math B Part 2 Kindergarten $12.99 Only 2 available