According to Ayana Lange at https://www.dailyinfographic.com/whistling-while-working-helps-productivity on May 24, 2017:

> 90% of workers say they perform better when listening to music.

> 88% report their production is more accurate.

> 77% of small- & medium-sized businesses believe music improves worker morale.

> 65% of employers believe music increases productivity.

> 61% of workers say they listen to music at work to make them happier and more productive.

> 40% of employers believe that music increases sales.

Why?  Music releases dopamine in the reward center of the brain.

Every Lesson-Up lesson plan incorporates a song which reinforces what is being learned.