Item: tExplicitOtherRecursive2b
Stem:
The first four terms of a sequence are given below.
Choose the algebraic expression that represents the nth term in this sequence.
. . .
Key:
- Observable: 1.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, that's not the correct answer. It looks like you may have confused
some of the numbers in the denominator. For problems
like these, it helps to try to apply the expression to all the terms in
the sequence. The correct answer is 1/(2n+6).
-
Teacher:The student got this item correct.
- Observable: 2.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, that's not the correct answer. It looks like you chose an expression
that might work for arithmetic sequences, but that wasn't the right thing
to do. For problems
like these, it helps to try to apply the expression to all the terms in
the sequence. The correct answer is 1/(2n+6).
-
Teacher:The student got this item correct.
- Observable: 3.
Score: 0;
Evidence Value: 0.
-
Student:Good try, but not quite right.
The main problem with that choice is that it won't generate
fractions. For problems
like these, it helps to try to apply the expression to all the terms in
the sequence. The correct answer is 1/(2n+6).
-
Teacher:The student got this item correct.
- Observable: 4.
Score: 1;
Evidence Value: 1.
-
Student:Right!
-
Teacher:The student got this item correct.
- Observable: 5.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, that's not the correct answer.
It looks like you may have confused
some of the numbers in the denominator. For problems
like these, it helps to try to apply the expression to all the terms in
the sequence. The correct answer is 1/(2n+6).
-
Teacher:The student got this item correct.
Metadata:
Item Node: tExplicitOtherRecursive2b,
Difficulty: 2.
Proficiencies: ExplicitOtherRecursive.