Screening River Rocks in 2nd Grade!

We have begun looking at a river rock mixture.  These rocks are found at the river bank - where the river and land meet.  

After looking at the mixture, we noticed there were different sizes and colors of rocks.  We even found small pieces of mica and pyrite (fool's gold) in the mixture.

After learning that some people use this mixture to make roads, sidewalks and other structures, we experimented with three different sized mesh screens to see what happened when the mixture was poured over them.

The large rocks stay on the large screen,
the medium sized rocks stay on the medium screen,
the small rocks stay on the small screen,
and the teeny rocks fall through all three screens!

The mixture that fell through the screen is more colorful
than the rocks that stayed on the screen.

The sand is so soft.

We tried putting the mixture through all three screens at once.
It worked!

Sometimes you have to shake the screen so the smaller rocks
can get through.