Growing Patterns

{"questions":[{"content":"What comes next: 3, 6, 9, 12, ___?<br>[[input-1]]","widgets":{"input-1":{"type":"input","answer":"15"}},"hints":["The pattern adds 3."],"explanation":"12 + 3 = 15."},{"content":"What comes next: 20, 25, 30, ___?<br>[[input-2]]","widgets":{"input-2":{"type":"input","answer":"35"}},"hints":["The pattern adds 5."],"explanation":"30 + 5 = 35."},{"content":"What is the rule for 4, 8, 12, 16?<br>[[choice-3]]","widgets":{"choice-3":{"type":"choice","options":["Add 4","Add 2","Subtract 4","Double every term"],"answer":[0],"explanations":["Each term is 4 more than the previous term.","","",""]}},"hints":["Compare neighbouring terms."],"explanation":"Each term is 4 more than the previous term."},{"content":"A tile pattern has 2, 5, 8, and 11 tiles. How many tiles are in the next figure?<br>[[input-4]]","widgets":{"input-4":{"type":"input","answer":"14"}},"hints":["The number grows by 3."],"explanation":"11 + 3 = 14."}],"mix":1}