Ask whether the question is looking for information that can be regurgitated. Questions such as "What year was Martin Luther King assassinated?" are closed -- or lower-order -- questions because they are either correct or incorrect.
Decide if the question is open-ended. These types of questions require students to extrapolate information, speculate and offer their opinions. "What do you think would happen if we raised the temperature of the earth by 15 degrees?" requires students to speculate, as nobody knows for sure what the answer would be. Answers to open-ended questions often begin with "I think . . . " and continue with "because" to offer a reason.
Determine if the question requires students to use analysis. If the question requires them to break down a concept and identify reasons or motives or draw on generalizations, then it is a higher-order question. An example of an analysis question is "What would happen if China invaded North Korea?" A higher-level answer would be along the lines of "It is unlikely that China will invade North Korea, because . . . ."
Scrutinize the answer for inference. Asking, "What would life be like if we could live on Mars?" requires students to speculate. At the synthesis level, students have to be able to engage in original and creative thinking to solve problems. "We would have to adapt our lifestyles to live on Mars, because . . . " is the sort of answer to expect.
Evaluate the evaluation. This level of higher-order questions and answers -- "Do you think the money spent on the space program would be better spent on health? Why?" -- requires students to offer opinions and to offer evidence to support their positions. A higher-level answer to a "why" question requires students to provide evidence to back up their answer, rather than leaving it as "because I think so."