How would you deal with a school district who has denied single subject acceleration on the basis of a WISC test, even though the child ( 4th grade) has a portfolio demonstrating mastery of the subject and a high school math teacher and college mathematics professor advocating on his behalf? The child has almost finished 75% of an algebra 1 course, working independently on his own. His passion is math and he constantly reminds us that he wants to be placed in a challenging curriculum. So far the school refuses to accommodate him in any way.

I'm sorry, but I would just call this a typical public school. Depending on your state, they have no legal responsibility to accommodate the gifted, no resources to do so, and no incentive to do so (I would imagine your dc raises the school's mean math scores). On top of that, there are likely nontrivial administrative problems in getting a 4th grader into a middle- or high-school algebra class daily.

I'm not excusing their decision. Ideally, your dc would receive an appropriate education. We gave up trying to get one from the public schools. We afterschooled intensively, and now we homeschool.

What is the issue / their policy related to the WISC?

What is the district's policy on acceleration? Get it in writing.

What is the state's law about acceleration? Get that too.

Also, what provision is made in your state for partial homeschooling?

Those will tell you what your options are. If what the district is doing is against state law or its own policy, you have recourse to those. If not, and if this is important enough to you and your child, you may need to look for alternative school options.

It may be possible for you to register as homeschooling in math, and use a curriculum that lets him fly at his own pace.

It may be possible to look at other local schools or districts and see if there's a better option out there.

You may want to find an educational advocate to help you make the case.

Some districts require their own testing for acceleration, and often the requirements are so severe as to be ridiculous. Some really do let the child move ahead without much fuss.

You might read their mission and 5 year goal statements and interpret them to serve your child's needs. I.e. opportunity, challenges , high standards, college preparation etc.