Item: tExplicitArithmetic1a
Stem:
The first four terms of an arithmetic sequence are given below.
Choose the algebraic expression that represents the nth
term in this sequence.
2, 4, 6, 8, . . .
Options:
n - 2
2n
2n - 2
n + 2
2n + 2
Key:
- Observable: 2.
Score: 1;
Evidence Value: 1.
-
Student:Right! The expression you selected, 2n, is correct.
-
Teacher:The student got this item correct.
- Observable: 1.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, the expression you selected, n - 2, is incorrect. The sequence in the question is: 2, 4, 6, 8,... But the expression you selected describes the sequence: -1, 0, 1, 2,...
-
Teacher:The student did not get this item right.
- Observable: 3.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, the expression you selected, 2n - 2, is incorrect. The sequence in the question is: 2, 4, 6, 8,... But the expression you selected describes the sequence: 0, 2, 4, 6,...
-
Teacher:The student did not get this item right.
- Observable: 4.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, the expression you selected, n + 2, is incorrect. You have found the correct recursive formula, but this is not the same as finding an expression for the nth term. The sequence in the question is: 2, 4, 6, 8,... and the expression you selected describes the sequence: 3, 4, 5, 6,...
-
Teacher:The student did not get this item right.
- Observable: 5.
Score: 0;
Evidence Value: 0.
-
Student:Sorry, the expression you selected, 2n + 2, is incorrect. The sequence in the question is: 2, 4, 6, 8,... But the expression you selected describes the sequence: 4, 6, 8, 10,...
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Teacher:The student did not get this item right.
Metadata:
Item Node: tExplicitArithmetic1a,
Difficulty: 1.
Proficiencies: ExplicitArithmetic.