The sand pendulum is one of the most enticing activities, where children can independently do everything by themselves. They do not want to lose control of the cup, and love swinging it the way they like, in different directions. Children can even adjust the length of the thread, change the type of cup and control the amount of sand to form extremely interesting patterns with different combinations of their own liking.
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https://www.youtube.com/watch?v=tR022ouh1BU