I found this app to be a great tool to use for the spelling of various vocabulary words in Spanish. Teachers can assign the category they want the students to practice with or the students can pick by category. Some of the topics students can pick from are numbers, clothing, verbs, body parts house, etc. In my curriculum we don't teach all of the vocabulary presented, yet they can use the letter choices given to attempt at the spelling and they are learning a new vocabulary word for the picture given.
Reading comprehension is a matter of decoding, reading speed, and critical thinking about the text, all of which can improve with tiered practice. (Se our post here on 50 apps for struggling readers.) So below, in an order of general complexity, are 15 apps for improved reading comprehension, ranging from word and sentence fluency, to recall, to critical thinking skills, to reading speed.