Why multiple choice?

When we released TTUltra we had made a deliberate decision to use multiple choice answers. Many time table apps use a keypad to enter the answer and initially TTUltra did the same. However, we felt that it was not the best solution because the actual entering of the number can cause problems. This is particularly true if you are trying to answer as quickly as possible. It’s all too easy to hit the wrong key and so enter the wrong answer – even adults do it.

Early version of TTUltra with keypad answer entry

In school, many children write their answers on paper and there are indeed several apps that use the writing recognition method. Unfortunately, in our tests, we found that getting the computer to reliably understand what the child has written was difficult. It could easily be very frustrating for some children and can lead to them getting the answer “wrong” through no fault of their own.

When we thought more about this, we realised that children who are learning to write simply don’t have the clearest hand writing. We saw several occasions where they tried to write the correct answer but the app’s hand-writing recognition processed it as a different number. The result was the question being marked wrong even though the child did actually know the correct answer.

We also thought about speech recognition, but this has the same sort of reliability issues as hand-writing. Plus, most parents enjoy peace and quiet (or would like to) and if their child spoke every single answer then they wouldn’t get any.

Three answers, only one is correct

In the end we decided that just displaying a correct answer and two wrong answers would be the best idea. If the child knows the answer, they can easily and quickly select the correct choice. What’s more, we very carefully select our wrong answers so they are close to the correct one. The child needs to be careful to select the correct option as (most of the time) it will not be obvious.

However, multiple choice does present another potential issue. You many be thinking, “surely a child can just randomly and quickly press any answer and they’ll get through a timed test with lots and lots of correct answers?” And indeed it could be possible for the child to get more correct answers by guessing than by slowly and carefully selecting the correct ones. If there were no barriers to this type of guessing, they could randomly answer 100 questions in a 2 minute game and get 33 right. A more careful child might only answer 20 questions and get 18 right in the same 2 minutes. However, TTUltra does puts barriers in the way of random answering…

Accuracy graph showing percentage of answers correct (in green), wrong (in red) and skipped (in orange). Simply guessing would show a very large gap between the green and red lines.

Firstly, TTUltra does not use a simple “how many questions did your child get correct” value internally and most of the graphs for parents don’t either. Only the ‘number answered correctly’ graph would do this and looking at the other graphs (particularly the ‘accuracy’ and ‘speed’ graphs) would show something was wrong.

Second and more importantly, our questions and space-race game are carefully set up so that guessing won’t normally win the race (see below). However, answering carefully and steadily will win races. This is because, if a child gets the question wrong, we show them the correct answer, leave it on screen for a short time (to let them take it in) and stalled their ship while this happens.

Correct answers give a boost

If they get the answer correct, their ship is instead boosted and they move (very quickly) on to the next question. In other words, a child who is guessing would (on average) be stalled in their attempt to high-speed answer questions more times that they were boosted. This stalling also means that a child who answers correctly (and gets another question quickly) is likely to be asked more questions than a child who simply guesses, opening the opportunity to get more questions correct in the timed test.

Of course, a child could randomly select all the questions correct but it’s statistically very unlikely. It’s far more likely they will get a few correct but far more wrong. In fact, pure guesswork from a choice of 3 answers would (on average) see a child get 1 in 3 (⅓ or 33.3%) correct and the rest (2 in 3) wrong. To put this another way, they would get twice as many wrong as right and so they’d be stalled more often that boosted. What’s more the chance of getting 10 questions correct in a row by guessing would be something like 1 in 59,000, 20 in a row would be about 1 in 3,500,000,000 (3.5 billion) and the above stated 33 would be around 1 in 5,500,000,000,000,000 (5.5 quadrillion)…

So, guessing is not likely to get a child very far.

Published by Neil

Head coder

%d bloggers like this: