Mariela learned how to affect change in objects directly within her reach.
Here, you see her touching the object.
In this photo, observe Mariela has made contact and said object is swinging much to her delight.
Here, she is reflecting on how this new skill may be parlayed into many years of grabbing objects and swinging them, throwing them, and generally making a huge mess so as to participate in the sibling ritual of destroying the house for Mama.