You may tell them that a symbol stands for the truth of the thing that it is a symbol of. Thus for example the flag of India is a symbol of what India stands for, that is to say, green for prosperity, growth, agriculture, saffron for strength, valour, sacrifice and, white for peace, purity with the dharma chakra or Ashok chakra in the centre representing the wheel of Dharma. So too the Mother and Sri Aurobindo’s symbols represent their various aspects, powers and the work that they came to do. If they ask more details you may refer them to write here and ask.
Lots of love always
Alok Da
