More Apps for students with special needs:

Higher level apps for high school students:
Math
Graphing Calculator-$1.99 scientific calculator
Algebra Pro- $.99 perfect for students in Algebra 1 or Algebra 2 tutorials included
SAT Math- FREE Your Teacher's SAT math app offers 175 SAT math lessons covering all of the core math concepts on the SAT!
Quick Graph FREE- powerful, high quality, graphic calculator that takes full advantage of the multitouch display and the powerful graphic capabilities of the iPad and iPhone, both in 2D and 3D.

Science
iElements- Periodic Table FREE-a simple periodic table of the chemical elements
iScience- $1.99 the perfect science reference- from branches of math, chemistry to physics

Notetaking Apps:
iThoughts- $9.99 Mindmapping is a great way for students to take notes. It helps students with key ideas in a graphic organizer.

English:
SAT and ACT Vocabulary Builder by AccelaStudy- $4.99 Using AccelaStudy's intuitive flashcard-like approach on your iPhone, iPod touch, and iPad, you can quickly expand your English vocabulary for university entrance exams, professional advancement, or simply increased language proficiency
Shakespeare FREE 41 plays, 154 sonnets and 6 poems.

Social Studies:
Global History Facts in a Flash$3.99- Global History study tool for your ipad- flash card app — with corresponding quizzes.
American Dreams-Speeches and Documents in US History-$1.99 FEATURING 480 DOCUMENTS, INCLUDING: 90 Supreme Court Decisions, all the US Presidential Inaugural Addresses, the Constitution and dozens of key laws, first-hand accounts and speeches (with 18 Audio Recordings) make this an incredible compilation of primary source documents in American History.
WolframAlpha- $1.99 Get answers. Access expert knowledge. Wherever you are. Whenever you need it.