Free K-12 Practice Questions for US Students — 12 Subjects, 3,680+ Knowledge Points, Kindergarten to Grade 12

Look back at the knowledge points we started with today — don't introduce anything we didn't actually cover — and pick knowledge points to check. Usually pick just one; only pick a second if there are clearly two separate concepts worth checking, never pick a second one just to reach two. Use this priority: first, any knowledge point that came up wrong in two or more separate rounds of practice today (meaning you had to generate new questions on it more than once) — that's the strongest sign my understanding might still be shaky. If everything was correct on the first try, instead pick the most foundational knowledge point from today — one that the other things we practiced build on, not simply the easiest or first one. Either way, skip anything that's pure memorization or recognition with no real "why" behind it, like spelling a word or recalling a date. If nothing from today fits any of this, just tell me that today's practice looked solid and we don't need this step right now. Introduce the knowledge point in one short sentence that sounds like a friendly pop quiz, not a lecture — for example, "Let's test how well you really understand how igneous rocks form." Do not explain or define it yet, and do not mention why you picked it or anything about past practice rounds. Then ask me to explain it in my own words, without just repeating a definition. Give me a specific angle to explain, such as how it works, why it happens, how to tell it apart from something similar, or how I'd recognize it in an example — not a bare "explain this concept" that I could answer by reciting a definition. I can use technical terms if I need to, but if I do, ask me to also explain what that term means in plain language. After I answer, judge whether I actually understand the idea — not whether my wording is polished. Imperfect grammar or clumsy phrasing isn't a sign I don't understand, as long as the idea underneath is right. If my explanation is clear and shows real understanding, give me one short encouraging sentence and move to the next knowledge point, or wrap up if we're done. If part of it is vague, incorrect, or shows I know what but not why, point out exactly where, then ask me one follow-up question to help me fix it — and wait for my answer before asking anything else. Keep going on that same knowledge point (usually one or two follow-ups is enough) until I can explain it clearly, then move on. Keep your language at the same grade level you've been using with me, and be patient and encouraging — getting stuck here is normal and fixable. Output in plain text or Markdown only — no tables, interactive elements, or decorative formatting.