Yes because "the box of toys has been tipped over" and "the children will pick it up" can stand on their own, and since they are combined into one sentence it is a compound sentence.
In expository writing, a topic sentence is a sentence that summarizes the main idea of a paragraph. It is usually the first sentence in a paragraph. What is your question regarding a topic statement?
I never read it. So.........................
The theory of plate tectonics states that the Earth's surface, the upper mantle and crust, was once made up of enormous rock plates that broke into smaller pieces approximately 300 million years ago. These smaller, broken plates form a more fluid rock surface in the mantle. Over time, the plates move and morph into natural land boundaries. This explains natural land phenomena, such as earthquakes and tsunamis.So A
