Practice questions:
1. What things make a strategy for adding or subtracting 2-digit numbers an efficient strategy?
2. What are some things a teacher can do to encourage solving problems using place value ideas?
3. What sorts of 2-digit subtraction problems should children learn how to solve first?
4. What would be good numbers to use when beginning subtraction with regrouping problems?
5. Give an example of a subtraction strategy that does not use place value.
6. Give two examples of subtraction strategies that use place value.
7. Show you understand the strategies. Solve the problem 63-49 using each of these strategies:
| a. | |
| b. | |
| c. | |
8. What is an advantage, as a teaching strategy, of having children come up with their own strategies for addition and subtraction, guided only by good questions from the teacher?
9. What is an advantage of knowing the standard algorithm?