Making derivatives essentially comes down to one trick: Tell OOo it's a fraction.
In other words, you have to use the “over" command. Combine this with either the letter “d" (for a total derivative) or the “partial" command (for a partial derivative) to achieve the effect of a derivative.
Markup
Result
{df} over {dx}
{partial f} over {partial y}
{partial^2 f} over {partial t^2}
Notice that we had to use squiggly brackets to make the derivative.