Explain · analogy · Like I'm five version
Why the Moon changes shape in terms of a pizza being eaten through the month
The Moon changes its shape every night just like a big, cheesy pizza being eaten by a hungry giant.
Imagine you have a lovely, round pepperoni pizza sitting in a box on your kitchen table. When the Moon is full and bright, that is like your whole pizza before anyone has taken a bite. Every night, the giant takes a small nibble off the side of the crust. As the giant eats more and more, the pizza gets thinner and curved until it looks just like a tiny slice or a fingernail.
After the giant has eaten almost the whole thing, the pizza seems to vanish into the dark sky. This is when the Moon disappears from our sight for a few nights. But do not worry, because the giant starts baking a brand new pizza every single month. Slowly, the crust grows back piece by piece until the big, round circle is back in the sky for us to see again.
It takes about four weeks for the giant to finish the meal and start the oven for the next one. The Moon does not really change its shape, but it looks different to us depending on how much sunlight hits it as it spins around the Earth. Just keep looking up, and soon your favourite pizza will be back on the menu in the night sky.
Where the analogy breaks downthe moon does not actually disappear or get eaten, it just gets covered by its own shadow.