Answers
1. Which CGI word problem type is most closely associated with the counting back strategy?
SRU--Separate, result unknown
2. For what sorts of numbers is counting back an efficient strategy? (Efficient means it can be reliably be used in a short amount of time--3 seconds of less).
Problems where the subtrahend is 1 or 2
3. Write a word problem for introducing counting back as a strategy.
The word problem should be an SRU, and the change amount should be 1 or 2.
4. Describe both ways of using counting back to solve the problem: 8-3
Way number 1:
8...
7 (put up a finger)
6 (put up a second finger)
5 (put up a third finger)
The answer is 5Way number 2:
8 (put up a finger)
7 (put up a second finger)
6 (put up a third finger)
The answer is 5.
5. What is a good thing to practice to help children be ready to use counting back as a strategy to solve problems?
Finding/telling the number that comes before a given number.
6. How can you use manipulatives to help children understand counting back as a strategy?
Hide a given number of counters (for example, hide 8 counters under a cup and tell the children that there are 8 under the cup)
Ask children to think quietly about how many will be left under the cup if you take out two.
Take out two counters one at a time. Ask the children how they figured out the answer.
7. What sorts of manipulative use encourages children to develop counting strategies for subtraction instead of direct modeling?
Manipulative problems where part of the manipulatives are hidden and can't be directly counted.