Calculators are great tools that allow the mathematical exploration and experimentation and thus enhance the students understanding of concepts. Before I go into the merits of the use of calculators in learning and how to efficiently use them I would like to, first, state the types of calculators available today.
We can sort calculators into two types. First is the calculator that evaluates expressions. This type is used to replace the manual time consuming paper and pencil arithmetic. The second type is the special functionality calculator for example the graphing calculator, the matrices calculator, the algebra calculator...etc. These calculators are used to explore concepts. Each type of calculator can fit in to mathematics education in its own unique way and needs the syllabuses to be specially written to incorporate it in the education system.
Recent studies show that calculators are evaluable tools for mathematics teaching. Instead of the student spending long time in tedious arithmetic calculations he can spend his time in developing and understanding principles and methods. Many students in the past have been turned off mathematics because of the time consuming tedious calculations and students who were efficient in these calculations were considered good at mathematics. Little attention was paid to the understanding of concepts. They hardly had anytime left to concentrate on concepts. Today with the use of calculators the students spend most of their time understanding concepts and the logic behind mathematics. They can relate the concepts to real life problems. The overall learning experience became richer. This is why calculators are recommended for all education classes from kindergarten to college and university.
Some may think that this way the student may become lazy. The reply to this is to consider you are giving a primary school student an exercise to solve; this exercise says that he has 100 dollars and went to the market and bought eight items of one commodity for a certain price and five items of another commodity for another price and he paid the 100 dollars then what is the remainder that he will take back. Now what is the mathematical quest of this problem? Is the question here how to do arithmetic multiplication, addition, and then subtraction? Or is the question that the student should know what is going to be multiplied by what and what is going to be added to what and then what is going to be subtracted from what? Indeed the mathematics of this problem is the procedure he is going to do to find the remainder and not the arithmetic process itself. In the past overwhelming the student with the arithmetic operations made many students miss the concept behind the problem. Some others did not miss the concept but were turned off altogether from mathematics because of the arithmetic operations.
Here I should emphasize that it is true that calculators are good for learning but still one must know how to make them fit neatly in the learning process. Students need to know the arithmetic hand calculations. They must study how to do that manually. When the prime concern of the mathematics exercise is how to do the arithmetic students should only use the calculator to check for the answer i.e. to see if it matches his hand calculations.
So I think the rule for using calculators is that the teacher should check the point of the mathematics exercise and its philosophy. If the calculator is doing a lower level job than the concept behind the mathematics exercise than it is fine. However, if the calculator is doing the intended job of the exercise then it should be used only to check the answer.
Moreover, education books should write examples that use calculators to investigate concepts and experiment with theories and teachers should lead students in classrooms and show them how to use these examples with calculators to explore concepts.