(CNN) When an elementary school in Texas picked happiness as this year's campus theme, a group of parents decided to bring the cheer straight to the students -- and to their bathrooms.

The parents worked for 37 hours last weekend to surprise the kids at Mary Moore Elementary School in Arlington.

Motivational messages of hope, kindness and unity are now artfully splashed across the fifth grade stalls and water fountains.

"The teachers work really hard, the students really apply themselves to get good test scores, so the parents wanted to add that theme of joy [to the atmosphere]," Principal Tyson Jones told CNN.

Almost 900 students are enrolled at Mary Moore. None of the students had any idea that the transformation was underway and were shocked when they returned to school on Monday, said Jones. The school was filled with smiles all day, and the kids took pride and ownership in the powerful project.

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