Was this a nasty thing to say?

So my little sister is only 12 and started in higher school recently. She has started new subjects also like science and music. She has only been doing science for 4 months and she has only done one exam but her teacher put on her report card after 4 months that she was a good student but that she was "weak" at science. My sister is upset and she will be studying science as a subject for the next 6 years. I think it was a nasty thing to write especially after doing a subject for 4 months. What do you think?

Was this a nasty thing to say?
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