One of my favorite warm-ups to do with kids is called Move and Shape - it manipulates the concept of a freeze dance to be a teacher guided exercise with more of a collective focus. We get our bodies moving and practice listening and seeing each other, all while having some structured creative freedom that wakes up the body and the mind.
The group begins in a circle. As the leader, I put on music and we all begin to move in place using a verb (I usually start with marching but any action verb that you are able to do in place will work - skipping, running, tiptoes, jumping, hopping). When I say, "Shape!" we freeze into a shape of our choice - each kid chooses their own shape. Shape in dance pertains to any frozen pose of the body, rather than a geometric shape.
This exercise is easily manipulated. The move (action verbs that can be done in place) can be different tempos (fast, slow) or qualities (heavy, light, under water, in outer space). The shape can also be improvised. I love to tell kids, "Make a new shape by moving one arm. Make a new shape by moving two knees and your head." The shapes can be different levels, use different body parts, connect to others, be different sizes, or show emotion. There are an endless variety of ways to manipulate the concept of shape.
I also love using this exercise as a warm-up in the math and movement classes I teach. Often during shape I will say something such as, "Show me a shape with parallel lines! Show my a shape that as an equilateral triangle! Show me a shape that as an obtuse angle!" The direction is specifically connected to the lesson we will be exploring later in class.
This exercise could also be done as a duet with a single child, such as your child. You can stand and face each other, warming your bodies up together to music you both love, while sharing eye contact and, hopefully, some good smiles.