Ten & tan

Now what is the problem with ten and tan? Well, not much, but to a five year old girl with quite an extensive vocabulary, she recognises both words and the two sounds the same. So, she spelled t-a-n instead of t-e-n in her exams. I guess the mummy should have gone through the spelling with her one day before the exams instead of 5 days earlier. But what the heck, she is only 5 years old!