By the time your child is ready for kindergarten or school, they should be able to recognize their own name and other simple written words. The sounds of each letter of the alphabet should be familiar to your child, and they should understand the principle of reading from left to right, which way to hold a book, and possibly even be starting to read three and four-letter words.
With adaptive learning, the programs won't move on to the next level until your child has a firm grasp on the current material. The online games will be a wonderful way for your child to catch up on basic arithmetic concepts and be comfortable using them across applications.
Quality worksheets for preschool can help you with a lot more than just academics. For example, once your child starts kindergarten, they will be expected to sit still and complete tasks for about 15 to 20 minutes at a time.
If your third grader needs help with math, there are many useful tools that can downloaded directly from the computer. Math is a subject that is best taught with visual aids, making the lessons more tangible for students.