Item: tExtendGeometric1a

Stem:

Extend the following sequence by giving the next two terms:

2, 6, 18, 54, 162, ...

Inputs:

1. Enter your answers here:
2. and

Key:

• Observable: 486, 1458. Score: 1; Evidence Value: 1.
  • Student:Right!
  • Teacher:The student correctly extended the sequence by finding the next two terms.
• Observable: 166, 170. Score: 0; Evidence Value: 0.
  • Student:Sorry, that's incorrect. It looks like you found the difference between the first two terms, and then used this difference to find the next two terms. This works for arithmetic sequences, but this is not an arithemetic sequence. It's a good idea to look at all the terms given in the question .
  • Teacher:The student looked at the difference between the first two terms, instead of looking at all the terms given in the question.
• Observable: 486, . Score: 0; Evidence Value: 0.
  • Student:Sorry, that's incorrect. Although you computed the next term correctly, It looks like you may have made a mistake computing the term after that. Check your calculations.
  • Teacher:The student may have made a computation error.
• Observable: 386, . Score: 0; Evidence Value: 0.
  • Student:Sorry, that's incorrect. It looks like you may have made a mistake computing the next term. Check your calculations.
  • Teacher:The student may have made a multiplication error.
• Observable: . Score: 0; Evidence Value: 0.
  • Student:Sorry, that was incorrect.
  • Teacher:The student got this item incorrect.

Metadata: