Oh, Squeaks.

I’m so sorry about your ball; I know it was your favorite. Squeaks was in the yard, playing with his favorite soccer ball, and he kicked it into a rock, and it popped! [Squeaks squeaks].

Oh, no, I don't think we'll be able to fix it. We could patch it, but the air would still leak out. If you want, maybe we could buy a new one. [Squeaks squeaks].

I know. You’re right — a new one won’t be the same, because this one will still be popped. It’s okay to be sad about it.

Everyone gets sad sometimes, and crying is a natural thing that can happen when we’re sad. It’s actually a really important thing our bodies do. Scientists aren’t completely sure why we cry when we’re sad, but they do have some guesses.

One of the main reasons has to do with what crying tells other people. When I see you crying, Squeaks, I know that you’re sad right away. You don’t even have to tell me with words — although it does help if you do.

The more I know about how you’re feeling, and the more you know about how I’m feeling, the better we can live together. If you’re really sad, or angry, or having other strong feelings, and I don’t know about it, then I might do something insensitive without realizing it and make things worse. For example, now probably wouldn’t be a good time to bring out /my/ favorite ball and go play with it in the yard.

It wouldn’t be a very nice thing to do when yours just popped. But if I didn’t know you were sad, I might not realize it would be hurtful. Knowing that you’re sad also means I can try to find ways to help, even if that’s just by staying with you until you feel better.

And remember the other day, when I was sad about the end of the book I was reading? You gave me a hug and I felt much better after that. I’m so glad that we can show or tell what we’re feeling so we can try to help each other.

And that’s really important outside of the Fort, too. The whole world is a much better place when you can help people who are sad or having a hard time. Besides for helping us share our feelings, scientists also think we cry when we’re sad because of what’s in our tears.

They’re mostly made of water, although there are some other ingredients, too. If you taste your tears, you can tell that they’re pretty salty. That’s because — you guessed it — they have salt in them.

And one of the other ingredients in tears is a painkiller — something that makes pain go away. It’s kind of like the medicine your doctor might give you when you’re sick, except this is something that your body makes by itself. So when you cry because you’re sad, your tears have something in them that can make you hurt less — even if it’s just your heart that hurts.

And then hopefully, when you’re done crying, you start to feel a little better. [Squeaks squeaks]. Do you think you’re starting to feel better? [Squeaks squeaks]. Oh, Im so glad!

And just like you’re already feeling a little better now, over time you’ll start to feel even less sad. It’s all part of understanding our feelings and the different ways we show them. Including by crying.

Thanks to everyone who asked us about why we cry when we’re sad. If you have other questions about feelings or the way our bodies work or or anything at all, you can ask a grown-up to help you leave a comment below, or send us an email at kids@scishow.com. We’ll see you next time, here at the Fort!