The Measured Mom-https://www.themeasuredmom.com/indoor-gross-motor-activities/
Gross motor Activities for Pre-K and Kindergarten to keep them active at home.
Hands on As We Grow- https://handsonaswegrow.com/gross-motor-activities-preschoolers/
Gross motor skills as well as active games to play with kindergartners.
Net Generation - https://netgeneration.usta.com/us-en/tennis-at-home.html
This a great website of tennis techniques you can do in your house with limited resources.