3-Digit Addition and Subtraction
Children's connections to their prior knowledge of basic facts and 2-digit addition and subtraction can help build their understanding of 3-digit addition and subtraction.
* Children will often invent strategies for addition and subtraction. Previously used strategies can be inefficient (e.g., draw a picture, use tally marks). It would be tedious for children to draw tally marks to add 268 + 453 or to subtract 459 - 122.
* Faced with inefficient methods, children are likely to develop strategies.
* These invented strategies can lead to the traditional algorithm.
Children may not see the need to regroup in subtraction. Instead of regrouping, children often find the differences between the two numbers, regardless of their position in the problem.
The process of adding and subtraction 3-digit numbers is dependent on children recognizing that 10 is the point at which they need to regroup. Providing children with opportunities to engage in discourse about the process and represent it with concrete objects or pictures helps foster their understanding of 3-digit addition and subtraction, with a firm foundation in place value.
* Children will often invent strategies for addition and subtraction. Previously used strategies can be inefficient (e.g., draw a picture, use tally marks). It would be tedious for children to draw tally marks to add 268 + 453 or to subtract 459 - 122.
* Faced with inefficient methods, children are likely to develop strategies.
* These invented strategies can lead to the traditional algorithm.
Children may not see the need to regroup in subtraction. Instead of regrouping, children often find the differences between the two numbers, regardless of their position in the problem.
The process of adding and subtraction 3-digit numbers is dependent on children recognizing that 10 is the point at which they need to regroup. Providing children with opportunities to engage in discourse about the process and represent it with concrete objects or pictures helps foster their understanding of 3-digit addition and subtraction, with a firm foundation in place value.
|
|
|