Have you ever looked at your family tree?
A family tree is a kind of diagram that, like all diagrams,
helps us connect separate pieces of information.
Diagrams can help make previously hidden information obvious.
Like how you're related to that one cousin.
Through your mother's father's brother of course!
Drawing diagrams can also be useful for solving really big problems;
problems like constructing the largest dam in the world over 16 years.
To see how one phase of construction is linked to the next,
and how much time each will take, we can use a diagram.
The diagram could help plan a schedule for building a temporary dam first.
They need to remove water from the construction site where the final dam will be.
A diagram could also help schedule digging an alternate channel
so the temporary dam can be built.
That way, ships can still travel on the Yangtze.
The chart might help show that this first phase must be completed in four years.
We can also see that Phase II cannot begin until Phase I is complete
and the damming of the river is successful.
It helps us see how each phase of construction will ideally take place,
and how it ought to progress over the years.
The diagram makes the relationship between Phase I and II clear.