Sometimes adults can grow impatient with children, when they seem unwilling to concentrate on a task as long as adults seem to be able to. But in fact, there may be no problem at all with the child, because they actually are spending just as much time on tasks as adults are able to - it's just that time is moving at a different rate for them!
There is a way to understand the difference between the attention span of a young child and that of an adult by considering the definition of time.
Aristotle's definition of "time" is "the measure of motion according to the before and after." This means that "time" is just a way of describing change and is not something that "exists" in its own right. Time does not exist outside the mind. Changes happen, but they don't measure themselves, and time is just a way of measuring changes. It's the human mind's way of understanding change. In philosophical jargon, it's a "mental abstraction with a basis in reality." That means that time doesn't exist in the real world but only in the mind; it's only the changes that time measures that are real.
This idea that time doesn't exist outside the mind may sound rather radical, especially if you're used to thinking in terms of relativity or time as a dimension. But this is one of the original definitions of time, which is still held today by many philosophers, especially among Thomistic philosophers.
There is some practical value to this understanding of time. It means that the expression "Time flies when you're having fun" is actually quite accurate. If time only exists in your mind, then it really can go "faster" or "slower" depending on the circumstances! The changes going on around you, or even within yourself, as still happening at the same speed. But time, which is the mind's perception of those changes, can really go faster or slower.
Now apply this concept of "time" to a child's mind.
What you find is that time goes faster for a child than it does for an adult. So it makes perfect sense that a child's attention span would seem shorter than an adult's. In fact, the child is easily able to spend the same amount of "time" as an adult on tasks. It's just that time is going by faster for a child than it is for an adult. So the same amount of time that the child spends is over faster than it is for an adult.
When I was little, it took forever for Christmas to come. The older I get, the quicker each successive Christmas comes. Has anyone else ever noticed this? It's not because of anticipation or excitement; it's because time slows down as you get older, so there is less time between any two dates the older one gets. That's what makes it seem to come faster and faster - because it really is coming faster, according to time as your mind is now sensing it.
Apply this to car rides. Isn't it true that a long car ride seems much longer to a child than to an adult? Try it out: if you used to take a long ride somewhere, on vacation perhaps, when you were little, try taking the same trip as an adult, and see if it takes the same amount of time. It will probably seem shorter, because it is taking less time, because time for you is moving more slowly as you get older. Less time passes between any successive changes.
Did movies seem longer when you were little than they do when you watch them now? I've noticed that. It's the same phenomenon again: time moves slower as you get older, so there is less time in 1 or 2 hours for you now than there was when you were younger.
It's good to consider this concept of time when dealing with children. Are children more impatient than adults? Sometimes it seems that way. But perhaps it is more often simply that waiting takes longer for a child than the same amount of waiting does for an adult.
If you're with kids on a long trip, keep in mind that a child is spending as much of his time sitting in the car for an hour as an adult would spend sitting in a car for an entire day. How do you feel after spending 12 or 18 hours riding? Like a child does after riding for an hour or two? This is easily explained by the concept of time as being something that only exists in the mind.
What about a child who is supposed to be ADHD? Isn't it possible that sometimes they are really behaving perfectly normally within their time frame, which is moving much faster than time is moving for the adults around them? It may also be that time goes faster for some children than for others.
This accelerated time is actually very beneficial for children. It enables children to learn faster, because it gives them more time to learn things. This can explain why children are able to pick up a new language quicker than an adult. If a child is exposed to a language for a week or a month, he is spending the same amount of his time in it as an adult would in many months or years. The more time one is exposed to another language, the more it is learned, and time goes faster for a child so he is spending more time with the language than an adult would be spending. The same goes for learning music or other skills: a child spends as much time practicing for an hour as an adult would if he spent the whole day doing nothing but practicing!
But the problem with their accelerated time is when adults are only willing to consider their own rate of time, and accuse children of having a low attention span, when in fact they have the same attention span - according to the speed at which time is moving for them.
This is good to keep in mind when working with children so you don't end up demanding more of them than you would expect from an adult, without realizing it.