You will certainly not gain her interest by teaching grammar. Grammar comes with use and experience, and you will be much more effective if you let her interests guide her studies, rather than vice versa. A colorful, modern multi-skills textbook geared to youth is the easiest way to experiment-- use the sections that interest her. Get her talking about what she likes to talk about, watch some videos of TV shows that she likes, and deal with the grammar and vocabulary problems as they arise in those contexts.
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