Michael Grup a, age 8, of Houston, Texas, for his question:

What is the longest river in the world?

There are three great rivers, all of them just about 4,000 miles long. One is the Nile of Africa, One is the Amazon of South America and the third is our own Missouri Mississippi river. No, we do not cheat by measuring both our big rivers, the Mississippi and the Missouri. We measure from the source of the Missouri to where it joins the Mississippi and from there the two rivers flow together end are measured as one to the sea. The experts tell us that actually the Missouri is the main river. The headwaters of the Mississippi is just one of its tributaries,

Our big, double river measures about 3,891 miles long and the mighty Amazon of South America is about 3,900 miles. The Nile of Africa measures about 4,161 miles   which makes it the longest river in the world.