Point out that another important property of sedimentary rocks is that individual grains are usually rounded. From colliding with each other while being transported. Sedimentary rocks become hardened when thick piles of sediment accumulate in layers that are later buried deep within the crust. Due to the tremendous weight of overlaying layers they become compacted causing water to be squeezed out of spaces between individual grains. Some minerals left behind to fill in these spaces later act as a cement bonding different loose grains together.
End result is layered rounded grains of sedimentary rocks.
Discuss where landforms of sedimentary rocks might be found on earth. Note that not all sedimentary rocks fit our description. A sample of rock taken from within a thick layer may not show layers within it and could contain sharp layers of broken rock. Layers and rounded grain are clues- not hard and fast rules. The second lesson is a continuation of the first where students are conducted outside with a spoon and a cup for each group and instructed to gather samples from various parts of the school grounds.