Chart is signed a lot like calendar, so be sure not to get the two confused. Hold your flat, non-dominant hand steady and horizontally to the side of your body. With the dominant number 4 hand, sweep down before the flat hand, dominant palm facing the other palm. Then sweep your '4' hand across the other hand again but horizontally, palms facing the same direction this time, mimicking the grid of a chart.
Teach your toddler the chart sign in the context of reviewing their numbers and alphabets, or household chores divided throughout the week, showing them options via a food chart, or going over a pedia chart that is tracking how tall they have grown over a period of time.
Teach your toddler this advanced sign when they are big enough to grasp the concepts of schedules, dividing simple tasks in the household, various categories, and so on.