To sign any contained body of water from lake to pond, first sign water, then make a visual circle with your hands indicating the sign of the body of water, by making the sign for area with your dominant hand.
Alternatively, for lake, starting from the ASL letter 'L' sign on both hands, hold them together near your body, then separating as they form a circle away from the body, end by joining your 'L' hands together again further in front of your body.
We use the sign for lake in preparation for our family vacation at the lake.
Most of us have a small lake nearby. We use the word lake to introduce our baby to bodies of water and help him or her understand the difference between a lake, a pool, and the ocean. We can teach our baby to sign lake contextually during afternoon walks, or we can teach the sign using the flash card.