Automatic text generators are at the heart of systems that provide use
rs with information. The trick is getting the system to answer follow-
up questions as naturally as possible. But even in moderately complex
domains, the task of handcrafting explanations using ''canned'' text o
r templates is so time-consuming and error-prone that it becomes infea
sible. Furthermore, these techniques cannot be extended to let a syste
m consider the user's prior knowledge, past problem-solving experience
s, or the preceding dialogue. To overcome these limitations, researche
rs have focused on automatically synthesizing text directly from under
lying knowledge bases. Automatic text-generation systems pose new oppo
rtunities-and new problems. Studies of human-human interactions show t
hat people often follow up requests for information with more question
s. This observation also underscores the need for computer-based infor
mation systems to let users ask follow-up questions. This capability i
s especially crucial in patient education, for example, where misunder
standings could have serious consequences. The ability to handle follo
w-up requests in context is essential, even crucial, to applications l
ike the patient education system described in this article. The direct
ion we've taken presents one alternative to full-fledged natural langu
age-understanding and makes it possible to design systems by adopting
a pragmatic (and possibly more useful) approach of generating choices
for the user. Our initial system evaluations reveal that users are com
fortable with the interface as a way to ask follow-up questions.