Abstract
The article investigates what strategies pupils use when solving two missing value word problems with the same mathematical model but different contexts. Both are examples of direct proportional problems.
The sample consists of 238 Grade 8 pupils and 175 Grade 9 pupils. Their written solutions were analysed in terms of their correctness and strategies used.
It was found out that the unit strategy, that is a pre-formal strategy, was by far the most frequent one. The context of the word problem influenced the choice of the strategy for nearly half of the pupils.
These pupils saw the two problems with the same mathematical model as belonging to two different classes of problems for which they had available different procedures. The use of formal procedures is less frequent as Grade 8 and 9 pupils do not have them fresh in mind.