35 words for the classroom, subjects and studying — each with the article a published German reference prints, not one a machine guessed. Grouped by gender, because that is how you have to remember them.
der, die and das keep the same three colours everywhere in German Growth, because the article is the part worth remembering and colour is what makes it stick. If the gender is what trips you up, the rules are here; if it is the way the article changes mid-sentence, that is the four cases.