Abstract: A system and method for encoding and then identifying a growth media from among a plurality of different growth media. A method is disclosed that includes: providing a set of tagging agents that are distinct from each of the different growth media; adding to each different growth media a unique subset of the tagging agents selected from the set of tagging agents in order to encode each different growth media; and determining an identity of one of the different growth media by detecting an existence of each tagging agent in the set of tagging agents.

Abstract: The present invention provides a handheld device for aiding students in solving mathematical problems. Rather than solving the problem for the student it provides a graphical environment where students can step through the solution process exactly as they would on paper. The invention monitors the solution process, reinforcing correct steps, pointing out errors in incorrect steps, and providing hints or help as required. The invention simply enforces the hard and fast rules of arithmetic and mathematics as the student performs steps in solving a problem and notifies the student when those rules are violated. This approach is in sharp contrast to other calculators which can only solve problems (or pieces of problems) for the student.

Abstract: A method and program for monitoring and checking students in solving mathematical problems are provided by the present invention. The invention monitors student choices as the student walks through the steps of solving a problem and provides feedback to the user indicating whether or not the user's input is correct. The invention determines if a newly entered statement correctly follows from the previous statement according to mathematical rules. The two statements are analyzed for common sub-expressions and compared against a database of mathematical rules. The database may include invalid rules corresponding to common mistakes. The invention then provides the user feedback in the form of the rule to which the user's input corresponds. If no rule is found in the database, a general error signal is provided.