Om pūrṇamadaḥ pūrṇamidam

(This Stotra is said without explaination of the meaning
since the concept is too dificult for the small child)

ऊँ पूर्णमदः पूर्णमिदम् पूर्णात पूर्णमुदच्यते ।
  पूर्णस्य पूर्णमादाय पूर्णमेवावशिष्यते ।।

OM pūrṇamadaḥ pūramidam
pūrāt pūramudacyate
pūrasya pūramādāya
pūramevāvaśiṣyate

That (God) is infinite; this (world) is whole;
from the infinite the world becomes manifest.
From the infinite, even if the whole is taken away,
what remains again is the infinite.