Math DJ into to Algebra app

I down loaded the free version.  Again the free version has only one chapter included with 30 problems to practice.  Each problem is for the most part a single step equation the student has to solve.  These problems are solved the same way as yesterday's app.  The student selects the correct number of bubbles with the letter so as to get the correct answer for the variable.  The problems start out easy but by problem 17 or so, they become much harder.  One example is 5G - 36 = -G which takes a bit more thought to solve.  If a student comes up with the wrong answer, it tells you that your answer is incorrect and to retry so a student must rework the problem till he gets it correct.  This app is one I could easily use in my lower  level algebra I class to help scaffold students who struggle with solving simple one step equations.  I much prefer this over the pre-algebra app for practice.