During the adorable class -- which also included food blogger Gaby Dalkin's 6-month-old daughter and makeup artist Kelsey Deenihan Fisher's 4-month-old daughter, both of whom are named Poppy -- all six babies laid around on blankets and, well, did what babies do: look absolutely adorable.
Tisdale posted a few photos of her own from the singing class, including another group shot that showed the infant students lined up in a row and camera ready.
"Cutest class," Tisdale captioned the sweet snap, before thanking Duff for hosting the playtime event.
Tisdale also shared a pair of pics of Jupiter laying on her back and gazing up into the camera. The first photo she captioned simply, "First Music Class."
The second photo showed Jupiter with her mouth open and, presumably, cooing or crying, which the proud mama captioned, "Trying to sing."
For more on the group of new moms and their super sweet bundles of joy, check out the video below!