Complex sentence: Many millions of years in the future an alien scientist experimenting with a time machine sends two test batches of educational toys to the past: one to the middle of the twentieth century and the second to the latter part of the nineteenth century.
Split into simpler sentences: Many millions of years in the future an alien scientist experimenting with a time machine sends two test batches of educational toys to the past. The first arrives the middle of the twentieth century and the second in the latter part of the nineteenth century.