I have been asked too many times how the examination items will change with the use of calculator being allowed in the PSLE. Logically, with the use of calculators being allowed, computation is no longer the skill being assessed. The examiners is more interested in how students make use of a computation to solve a problem. In other words, in some problems, a computation is necessary but not sufficient to obtain a solution.
The examiners are also able to use authentic information which often results in tedious computation not easily done mentally in the problems. With calculators the issue of tedious computation is non-existent.
We have always encouraged investigative problems in the curriculum but do not really assess thsi aspect of problem solving. Often in solving investigative problems, a fair bit of exploration and repetitive computation is necessary. Without calculators, such exploration and computation make it not plausible for investigative problems to be included in a timed test. With calculators, there is nothing to stop examiners from assessing such problems in a timed test.
Of course many of the problems that have been included in previous PSLE can still be included even when calculators are allowed. In some problems, calculators are simply not useful. In others calculators will provide help to those who stuggle with computations but otherwise fairly successful in problem solving. In the era where technology is prevalent, if all one cannot do is tedious computation, it is no longer perceived as having a big handicap. After all this weakness can be overcome by a relatively cheap tool - the calculator.
These are of course my views based on the role of calculators in doing mathematics at primary levels.