{
"rubric":"Help the train move forward by typing the right answer to score, then click on the balloon and drop it on the correct wagon.",
"attempts":"2",
"case_sense":"1",
  "Questions":[
    ["1. The sum of 345 + 278 is __________ .","623"],
    ["2. When we add 2,356 + 1,432, the sum is __________ .","3,788"],
    ["3. The sum of 246 + 318 + 175 is __________ .","739"],
    ["4. In addition, the order of numbers does not change the sum. This is called the __________ property of addition.","commutative"],
    ["5. The sum of 4,205 + 3,174 is __________ .","7,379"]
 
  ]
}