Prevent speed gaming of answers

I've discovered that my 6-year-old will speed-game the answers that he does not know. For example, he knows that 13 - 6 has an answer somewhere between 5 and 10 so he'll quickly type in 5, 6, 7... in under 2 seconds which enables him to answer the question in under 2 seconds which improves his chances of getting a gold badge for that round.

It should be pretty easy to penalize that type of system-gaming, ideas:

• Add a penalty time (e.g. 1 or 1.5 or 2 seconds) when too many answers are stringed together in a short time period.
• Easier: If time for a question qualifies for a high value badge and lots wrong then add penalty time to that question.

From a UI perspective need to make it clear that the system-gaming is being penalized. I think that a red skull-and-crossbones at the end of the question would be a good indicator. Knowing my kid though I think that he'd have fun collecting those so that also might backfire and a different negative badge would be needed.

Think out aloud:

Time         # wrong          Penalty Seconds
<2             1                   0.25
<2             2                   0.75
<2             3                   1.5
<2             4>=                 2.25
<3             2                   0.25
<3             3                   0.75
<3             4>=                 1.5
<4             3                   0.25
<4             4>=                 0.75

No files, tests, or entry points are identified. First locate the answer-timing, badge-calculation, and end-of-question UI logic, then clarify the penalty rules and indicator design; done means agreed behavior is implemented and verified for the listed timing and wrong-answer cases.