以下是一首关于英语比较级的儿歌，歌词简单易懂，适合儿童学习：

Title: Big, Bigger, Biggest

Verse 1:

I have a cat, it's very small,

But it's the smallest cat in the hall.

It's so small, it fits in my hand,

But it's not the smallest, oh no, no.

Chorus:

Big, bigger, biggest,

Big, bigger, biggest.

Big, bigger, biggest,

In the world, it's the best.

Verse 2:

I have a dog, it's very big,

But it's not the biggest dog in the rig.

It's so big, it can't fit in my bed,

But it's not the biggest, oh no, no.

Chorus:

Big, bigger, biggest,

Big, bigger, biggest.

Big, bigger, biggest,

In the world, it's the best.

Verse 3:

I have a bird, it's very loud,

But it's not the loudest bird in the cloud.

It's so loud, it makes my ears ring,

But it's not the loudest, oh no, no.

Chorus:

Big, bigger, biggest,

Big, bigger, biggest.

Big, bigger, biggest,

In the world, it's the best.

Bridge:

Now let's compare, big, bigger, biggest,

In the world, it's the best.

Big, bigger, biggest,

We'll remember, big, bigger, biggest.

Chorus:

Big, bigger, biggest,

Big, bigger, biggest.

Big, bigger, biggest,

In the world, it's the best.

通过这首儿歌，孩子们可以轻松地学习比较级的用法，并享受学习英语的乐趣。