This article is about problems that children may have when learning mathematics, problems that are also typified in publications as 'dyscalculia'. We consider two questions. The first: Is a child a dyscalculic if it runs into trouble learning mathematics? The second: Does a child have problems when learning mathematics because it experiences dyscalculia? In both cases, we must know what are the troubles that occur when learning mathematics and what it means to 'experiences dyscalculia'. We consider these questions based on 'Open Minded Research' (OMR), especially the theories of 'realistic mathematics education' (Freudenthal, 1991) and the cultural-historical theory (Vygotskij, 1978; Leont'ev, 1979). OMR is context-embedded, and the researcher and child are always in discussion about problems that are meaningful to the child. Our approach is not based on a theory of dyscalculia; indeed, there is no accepted definition of dyscalculia (Trott, 1974). We prefer research -- like OMR -- based on studies and observations of the thinking activities of a child that experiences problems when learning mathematics. Butterworth (2019, 2022), a leading researcher of dyscalculia, claims that dyscalculia is connected with an 'inherited domain-specific capacity', called 'the number module'. He presents research that shows that, when this module fails to work, the result will be a 'core deficit' for number reasoning. The question we discuss is whether this low number sense must be considered as -- and is connected with -- a genetic disorder (a core deficit) in the child's brain? Or is it an indication that the child needs special ortho-educational support? We prefer the second view as we suppose that there is indeed a connection, but not a causal one, but rather a correlational one. If dyscalculia is a matter of genetics, there is not so much help a teacher can give a child. If, however, a 'failing number module' is a signal that the child may experience trouble when learning mathematics, there may be more that can still be done. Children, moreover, are very different in their capacities and they can be endowed with a differentiated intraindividual ability profile (Vaughn & Linan-Thompson, 2003). And sometimes it happens that children are not so good in mathematics, while they are average -- or even excellent -- in other disciplines. So, a limited, innate talent or potential for mathematics can cause problems. Another difficulty may be that mathematics education at school is particularly 'practice and drill' ('mechanistic') without stimulating interaction, reflection and meaning. Children's understanding of the (mathematical) world, however, is strongly connected with their construction of meanings (Walkerdine, 1997). That is why familiar contexts should be the basis of mathematics education, as well as of remediation for children with learning problems. Reflection gives insight into one's own thinking activity, while interaction and reflection are indispensable sources for helping children with learning problems. Familiar contexts are very suitable for children who suffer 'mathematics anxiety' and may have a fear of 'cold', abstract numbers.