I have noticed that children can learn so much about things that they are interested in -- they remember every small detail about the fish that they caught and helped Dad clean. They remember with clarity the time that they toured the Corvette factory and can share their adventure to the last detail with anyone that asks. They can name the stars and major constellations after spending nights in the backyard with Mom or Dad and a telescope. While investigating an interest in baseball, they can tell you all about Babe Ruth, Satchel Paige, Hank Aaron and more, but they can't necessarily tell you the years that they played.
With my own crew, I learned that there was an age or level of development where they could begin to put things in order time-wise - understand the concept of the American Revolution coming before the Civil War, for example. Before they reached this point, their interests were more pressing in their minds than the order that things happened. To help them begin to understand the concept of time, timelines are invaluable.
For example, the study of baseball started our study of the Civil War, as we discovered that the game was spread from north to south in prison camps during the Civil War. While they were fascinated with baseball/softball at the moment, the Civil War caught their interest -- what was it, why were Americans fighting Americans, etc.
While working on Gardens, we discovered that Gregor Mendel (Father of Genetics using sweet pea plants) worked on his research across the Atlantic Ocean during the Civil War and had his paper presented to the European scientific community in 1866, right after the end of the Civil War.
All of this to say that sometimes the interest that they are following can reveal other areas of interest that become a fascination. I quickly learned that it is more fruitful to follow that interest, pointing out connections to other things that have been studied. It is helpful to have them create timelines as the study progresses, so that they can see the overlaps - Mendel's work, Baseball, Civil War, etc.
I've noticed that this gives them a framework on which they can "hang" the information. They also can see that nothing happens that is just science or history or art -- God weaves the events together in such amazing ways.
The timeline also helps them learn that events are happening all over the world simultaneously. In 1862, in the middle of the Civil War, President Lincoln signed the bill authorizing the building of the Transcontinental Railroad (Trains). In 1863, the first section of London's Underground Railway opened. Also in 1863, both Henry Ford and Henry Royce were born -- to later become leaders in the development of the automobile...
I have an analogy that helps me understand a child's mind -- a child's mind is similar to the storage area on the top of an old- fashioned rolltop desk. There are all kinds of cubbyholes and nooks and crannies to be filled. When children are young, they can put all kinds of things in those compartments, and know all about each one. They know just where each morsel is, and know just how it relates to other pieces (baseball to civil war to trains). As they grow older, they begin to sort and arrange the information in the desktop, based on time, interest, etc.
So, there you have my theory about kids and interests and their concept of time. But who am I to tell you that? You know firsthand that they don't understand the concept of wait, or not right now, or just a few more minutes! <smile>