i) 16, 32, 64
ii) multiply by two (or double)
Accept:
13, 19, 26 and +4, +5, +6, +7 (increasing by an incrementing amount); and
12, 20, 32 and 4+8=12, 8+12=20, 12+20=32 (Fibonacci pattern);
Other sequences with a rule stated and consistently applied.
moderate
Based on a representative sample of 192 students.
NOTE: Answers for a) and b) are interchangeable.
Next steps:
Encourage students to find a general rule that applies to all numbers in the sequence/pattern, and explore the use of operators other than addition when identifying rules for sequences.