Here are three videos. YouTube now has an app for children. Another is about why vaccines work. The last is about how you investigate hypotheses.

Here is a fun number: 2519.

When you divide it by 2, the remainder is 1.

When you divide it by 3, the remainder is 2.

When you divide it by 4, the remainder is 3.

When you divide it by 5, the remainder is 4.

When you divide it by 6, the remainder is 5.

When you divide it by 7, the remainder is 6.

When you divide it by 8, the remainder is 7.

When you divide it by 9, the remainder is 8.

When you divide it by 10, the remainder is 9.

*Image Credits: YouTube for the kids app logo*