Arrays Check

{"questions":[{"content":"A 5-by-4 array contains how many objects?<br>[[input-1]]","widgets":{"input-1":{"type":"input","answer":"20"}},"hints":["Multiply 5 by 4."],"explanation":"5 × 4 = 20."},{"content":"An array has 7 rows of 3 tiles. How many tiles are there?<br>[[input-2]]","widgets":{"input-2":{"type":"input","answer":"21"}},"hints":["Multiply rows by tiles per row."],"explanation":"7 × 3 = 21."},{"content":"A 24-dot array has 4 equal rows. How many dots are in each row?<br>[[input-3]]","widgets":{"input-3":{"type":"input","answer":"6"}},"hints":["Divide the total by rows."],"explanation":"24 ÷ 4 = 6."},{"content":"Which description matches 6 × 5?<br>[[choice-4]]","widgets":{"choice-4":{"type":"choice","options":["6 rows of 5","6 rows of 6","5 objects altogether","6 + 5 rows"],"answer":[0],"explanations":["Six rows of five show 6 × 5.","","",""]}},"hints":["The first factor can describe rows."],"explanation":"Six rows of five show 6 × 5."},{"content":"A 3-by-8 array is turned around. Which fact describes it now?<br>[[choice-5]]","widgets":{"choice-5":{"type":"choice","options":["8 × 3","3 + 8","8 − 3","24 × 3"],"answer":[0],"explanations":["The same 24 objects form an 8-by-3 array.","","",""]}},"hints":["Turning swaps rows and columns."],"explanation":"The same 24 objects form an 8-by-3 array."},{"content":"An array has 9 columns and 2 objects in each column. How many objects are there?<br>[[input-6]]","widgets":{"input-6":{"type":"input","answer":"18"}},"hints":["Multiply columns by objects per column."],"explanation":"9 × 2 = 18."},{"content":"Thirty-five counters form 5 equal rows. How many counters are in each row?<br>[[input-7]]","widgets":{"input-7":{"type":"input","answer":"7"}},"hints":["Use 35 ÷ 5."],"explanation":"Each row has 7 counters."},{"content":"Why is an arrangement of rows 2, 3, and 2 not an array?<br>[[choice-8]]","widgets":{"choice-8":{"type":"choice","options":["Its rows are not equal","It has too many objects","Arrays cannot have rows","All arrays must be square"],"answer":[0],"explanations":["The row lengths differ, so the arrangement is not a rectangular array.","","",""]}},"hints":["Arrays need equal rows and columns."],"explanation":"The row lengths differ, so the arrangement is not a rectangular array."}],"mix":1}