This is a good question and does not have a pat answer.  dgraab has offered some good ideas and suggestions to consider.  The amount of homework assigned for lst graders has probably increased since parents were in first grade. Schools today are dedicated to students reaching certain standards and succeeding in standardized testing.

If your little girl is getting homework only on Monday and has three days to complete this, it might be reasonable. Typical is hard to determine without doing research on many first grades and comparing the information.

However, the amount of assigned homework that a little one can reasonably manage may very day to day and week to week.  What your own child can handle is an important issue to observe and address.  Here is what I advise the parents I work with.  Help your son/daughter with the work as your time allows.  Offer breaks from the work and snacks as the attention span requires.  Give encouragement and if she fizzles out, refrain from seeing this as a failure or getting too worried.
Send a note in to the teacher the next day with the reason and the area she needs to be helped with.

If you see a chronic problem with the volume of work develop for your child over time, do set up an appointment and talk to the teacher about your daughter's individual needs. You may or may not be able to affect the way the teacher assigns work in general, but you might have a chance of impacting what needs to happen for your child.  Always take a collaborative approach when meeting with the teacher.  You are on the same team working for your child's academic and life success.

Bette J. Freedson, LICSW, LCSW, CGP

JustAsk Expert
http://www.singlemomsos.com/index.html