{
    "name": "Daily Bell Ringers Library",
    "description": "Free bell ringers (3–5 minute classroom warm-ups) for grades 6–12, with answers and teacher notes.",
    "url": "https://dailybellringers.org/bell-ringer-library/science/",
    "license": "https://creativecommons.org/licenses/by-nc/4.0/",
    "credit": "Daily Bell Ringers (dailybellringers.org)",
    "filters": {
        "subject": "Science",
        "grade": "All"
    },
    "generated": "2026-10-13T16:22:31+00:00",
    "count": 4,
    "items": [
        {
            "id": 86,
            "date": "2026-10-13",
            "grade": "Grades 9–12",
            "subject": "Science",
            "topic": "Balancing the equation for burning methane",
            "prompt": "Natural gas is mostly methane (CH4). When it burns completely, it reacts with oxygen to make carbon dioxide and water. Balance the equation, then prove it is balanced by counting atoms on each side.\n__ CH4 + __ O2 → __ CO2 + __ H2O",
            "answer": "CH4 + 2 O2 → CO2 + 2 H2O\nAtom count: carbon 1 = 1. Hydrogen 4 = 2 × 2 = 4. Oxygen 2 × 2 = 4 on the left; 2 (in CO2) + 2 × 1 (in water) = 4 on the right. Tip: balance C and H first, then O last, since oxygen shows up in both products. Students who change subscripts (writing H4O) have changed the substance, not balanced it.\nSource: U.S. Energy Information Administration: Natural Gas Explained",
            "sources": "https://www.eia.gov/energyexplained/natural-gas/",
            "url": "https://dailybellringers.org/bell-ringer/science-bell-ringer-grades-9-12-balancing-the-equation-for-burning-methane/",
            "set_url": "https://dailybellringers.org/bell-ringers-grades-9-12-2026-10-13/",
            "pin": "https://dailybellringers.org/wp-content/uploads/pins/lib-science-bell-ringer-grades-9-12-balancing-the-equation-for-burning-methane.png?v=324bea43"
        },
        {
            "id": 81,
            "date": "2026-10-13",
            "grade": "Grades 6–8",
            "subject": "Science",
            "topic": "Why ice floats",
            "prompt": "Most substances get denser when they freeze, so the solid sinks in its own liquid. Water is different: ice floats. Explain why, and predict about how much of an ice cube sits above the water line.",
            "answer": "When water freezes, its molecules line up in a regular pattern (a lattice) that holds them farther apart than in liquid water. That makes ice about 9 percent less dense than liquid water, and anything less dense than water floats. Because ice's density is about 90 percent of water's, roughly 10 percent of an ice cube or iceberg sits above the surface.\nExtension: why does it matter for fish that lakes freeze from the top down instead of the bottom up?\nSource: USGS Water Science School: Water Density",
            "sources": "https://www.usgs.gov/special-topics/water-science-school/science/water-density",
            "url": "https://dailybellringers.org/bell-ringer/science-bell-ringer-grades-6-8-why-ice-floats/",
            "set_url": "https://dailybellringers.org/bell-ringers-grades-6-8-2026-10-13/",
            "pin": "https://dailybellringers.org/wp-content/uploads/pins/lib-science-bell-ringer-grades-6-8-why-ice-floats.png?v=845cf051"
        },
        {
            "id": 71,
            "date": "2026-10-12",
            "grade": "Grades 6–8",
            "subject": "Science",
            "topic": "Why the Orionid meteor shower returns every October",
            "prompt": "Every October, Earth passes through dust left behind by Halley's Comet, and we see the Orionid meteor shower. Why does the same meteor shower show up around the same dates every year?",
            "answer": "The comet's dust is spread along its orbit. Earth's orbit crosses that dusty path at the same point each year, so we run into it around the same time every October. The Orionids are active from early October to early November, peaking around October 21–22.\nSource: NASA: Orionids Meteor Shower",
            "sources": "https://science.nasa.gov/solar-system/meteors-meteorites/orionids/",
            "url": "https://dailybellringers.org/bell-ringer/science-bell-ringer-grades-6-8-why-the-orionid-meteor-shower-returns-every/",
            "set_url": "https://dailybellringers.org/bell-ringers-grades-6-8-2026-10-12/",
            "pin": "https://dailybellringers.org/wp-content/uploads/pins/lib-science-bell-ringer-grades-6-8-why-the-orionid-meteor-shower-returns-every.png?v=90ba29d1"
        },
        {
            "id": 76,
            "date": "2026-10-12",
            "grade": "Grades 9–12",
            "subject": "Science",
            "topic": "The physics of a 66-kilometer-per-second meteor",
            "prompt": "Orionid meteors enter Earth's atmosphere at about 66 kilometers per second. (a) How far does one travel in 3 seconds? (b) The grains are about the size of sand. Why do they glow and burn up instead of reaching the ground?",
            "answer": "(a) 66 km/s × 3 s = 198 km.\n(b) At that speed the grain slams into the air in front of it. That air is squeezed and heated so fast that the grain heats up and vaporizes, which is the streak of light we see. Students often say \"friction\"; that is part of it, but compressed, superheated air does most of the work.\nSource: NASA: Orionids Meteor Shower",
            "sources": "https://science.nasa.gov/solar-system/meteors-meteorites/orionids/",
            "url": "https://dailybellringers.org/bell-ringer/science-bell-ringer-grades-9-12-the-physics-of-a-66-kilometer-per-second-meteor/",
            "set_url": "https://dailybellringers.org/bell-ringers-grades-9-12-2026-10-12/",
            "pin": "https://dailybellringers.org/wp-content/uploads/pins/lib-science-bell-ringer-grades-9-12-the-physics-of-a-66-kilometer-per-second-meteor.png?v=e6d89ed8"
        }
    ]
}