Wednesday, November 18, 2009

What is in a question?

I have finally returned to adding some new material. As part of my teaching experience, I am currently taking a class in Science teaching methods. My professor has a very interesting method for using multiple choice questions to promote higher order thinking. You can view some of the discussion at the blog:

http://problemfinding.labanca.net/

On one of his other blogs, he gives an example of a multiple choice question that requires quite a bit of thought. Here is the question from my professor:

Q. Insects with wing mutations that prevent flight (e.g., in fruit flies, some flies have crumpled wings throughout their lives) usually can’t survive long in nature. Flightlessness is selected against. But in three of the following environments the trait could actually be selected for. In which environment would useless wings NOT be selected for?

MY professor uses multiple choice questions to stimulate higher order thinking instead of simply testing for recall of knowledge or facts. Here are my thoughts on his different multiple choice options:

a. an island where stiff winds blow some flying insects out to sea, never to return.

I did not think that this was the best because of the fact that only some flying insects were blown out to sea. Fruit flies that had crumpled wings would be less likely to be selected against, yet not all of the un-mutated flies would necessarily be sent out to sea – so who is more likely to survive – a lessened population of un-mutated flies or a mutated crumpled wing fly?

b. a swamp full of frogs that can see and catch flying insects better than crawling insects.

I also did not think that this was the best answer. One reason is that e the entire island is not likely to be covered by one swamp. Therefore, even though the swamp frogs may have a negative effect on the population of fruit flies, this does not mean that fruit flies with wings will be selected over crumpled-winged flies. Rather, winged flies will be under more pressure as they are more likely to be targeted in the swampy area.

Also, this statement does not say that frogs cannot catch crumpled winged flies, only that they can see and catch flying insects better. So, the inference is that they may also be able to catch crumpled-winged flies, but that catching the flying ones is only easier.

c. a forest full of bats that catch and eat insects while in flight.
In my mind, this would be the best answer of where useable wings would be selected against and useless wings would be selected for and not against.

My reasoning for this is that useless wings would NOT be selected because flying bats in a forest would be eating only the fruit flies with usable wings as they, “Catch and east insects while in flight” and only un-mutated fruit flies can fly so only un-mutated fruit flies can be eaten and selected against.

The inference in this answer is that the bats do not eat insects on the ground. Given my knowledge of bats and the way the choice is worded, that should be a fair assumption.

d. a cage with predators, who crawl along the base

This seemed like the “chestnut” – my term for the easy answer. Certainly the crumpled wings would be selected against since flying insects could fly away and crumpled insects would be on the bottom of the cage and more easily caught.

Here is one possible issue with this answer – is a cage an environment? In the most narrow sense certainly, but would this environment really be an element of evolution or just a lab experiment?

With all that said, this would appear to be the clearest negative case of an environment where useless wings would be selected against, not for. So, going back to the wording of this question, “In which environment would useless wings NOT be selected for?” – this choice would best satisfy the task in my mind.

What is the point of all of this? For me, it was the thought provoking aspect of this question. Instead of just recalling a fact or concept, I was forced to apply my knowledge to think about the different responses. This HOTS (Higher Order Thinking Question) helped me to think and write more about the selection mechanism of evolution.

A note on question wording…

I would point out though, one issue that I myself would caution on using a question such as this, and that is that like many people, I have trouble with “NOT” questions. As part of our educational training, we have received instruction on avoiding the negative questions. After carefully re-reading the responses, I still almost went for choice c as this was the clearest case to me of winged flies being selected against.

However, this question asks in which environment “Would useless wings NOT be selected for. Clearly the best answer, in my mind is d. The problem that I had was keeping the “NOT” straight in my mind.

In the end, I had to go back a few times and re-read the question to be sure that I was clear on what was being asked. I think that as a teacher, it is important to help student not only with scientific material, it is also important for teachers to help students with skills.

In questions such as these, you may need to have a quick “mini-lesson” in test taking skills and help students to recognize these questions. One aid might be to train students to underline the word “NOT” in the question. Also you may want to help student organize their thinking and responses. For instance, a very quick “T” chart could be created showing environmental influences that would help winged flies on one side and crumple wings on another side.

Another idea is that students could be taught a very simple skill of writing out something like “Good for crumpled wings”, “Bad for crumpled wings”. This would help them think about the meaning of each choice and then be able to go back and re-read the question and provide the best answer.

A third strategy might be to have students re-write the question or at least re-think it in their own mind. In the specific example, I took the phrase, “In which environment would useless wing NOT be selected for”, and physically re-wrote it as, “In which environment would useless wing be selected against”. By re-writing, or re-thinking the question, I was able to more clearly understand the task at hand and this helped me to better answer the question.

These types of skill can help students to think more about their questions as well as gain more knowledge about their work with the side benefit of helping them achieve more on standardized tests that will inevitably come their way