Many entering first-grade children can use manipulative materials to represent the objects in orally stated problem; they can form groups, compare them, join them, separate them, and decompose them, as needed, to solve problems involving all four arithmetic operations.
Many entering first graders are much more comfortable with exchanging some units for a fixed group (i.e., when trading multibase arithmetic block units for a long, five pennies for a nickel, three yellow chips for a green one, etc.) than with exchanging a fixed group foe units. This seems to be particularly true if the exchange id needed to achieve another functional purpose such as taking away a group having more units than are directly available from the combination of groups and units. The question of what constitutes a "fair" trade within the context of what is a needed trade creates confusion in the minds of many children of this age.
Many entering first graders seem able to handle situations that require the joining of a number of equal-sized gruops. Whether this represents more than a repeated addition in their thinking is a good question. Some of the children indicated by comments and by the way they grouped the units that this was so. Others gave responses or grouped in ways that did not indicate a "repeated addition" kind of thinking. They could also use manipulative materials to work out both measurement and partitioning problems. This was important, since seeing 23 as two 10s and 3 required the application of the measurement idea of division.
Many entering first graders may not understand money relationships, an understanding sometimes assumed by text writers and teachers.
Many first graders may bring to the mathematics learning situation a theory of how things relate, a langue or a mode of interpretation different from that of the arranger of the situation, and consequently, they may solve "their" problems rather than those posed to them. Whether an action or a comparison is indicated by the language may make subtraction easier than addition. An exchange or grouping operation that results in more or fewer entities may lure the child into seeing a different problem from the one intended.