How big is the universe?

I was trying to explain to Mia, and referenced Men in Black. The universe is on orions belt, which means it's around the cats neck. Can you imagine an entire universe on the cats collar? Gets me thinking, and instead of the classic solar system, then beyond the solar system, then quantum physics infinite universe, I thought I'd try a new angle. How about a grain of sand on a beech, and how many grains of sand are there on a beech? Imagine one grain of sand contains a billion solar systems, and then imagine how many grains of sand are in each of them? 

Teaching infinity opens the mind.