The phrase "to access the curriculum" means to be able to participate and learn from the lessons and materials that have been planned and designed by teachers. Full definition
We define a child as having special educational needs if they have a greater difficulty accessing the curriculum compared with the majority of children of the same age. (inspirationtrust.org)
One in five pupils are at risk of leaving their primary school unable to read well enough to access the curriculum at secondary level. (schoolstogether.org)
I think sometimes helping a child access a curriculum by using chemicals to create what's presumably a chemical imbalance in a child's brain is an appropriate thing to do. (kidsinthehouse.com)