For a film about a frustrated, unhappy child educator, The Kindergarten Teacher is surprisingly quiet. No chaotic scenes of brats in meltdowns and screaming teachers wilting with stress. In fact, New York teacher Lisa Spinelli (Maggie Gyllenhaal) seems to have lucked out. Her little ones are well-behaved and she seems to genuinely like them, navigating her classroom with that airy, benign, vaguely lupine air Gyllenhaal does so well. Her days tick along in well-observed routine: cleaning toilets, pouring fruit juice and washing dishes in tiny sink. But there is unfulfilment seeping out of her. In the downtime it is deafening. Sara Colangelo’s…