The Motion of Particles

1. Period 1: Presentation slides 1-10 (phenomenon, targets, one substance in three states, the particle panels, solids, liquids, gases, the which-state check, vocabulary for the three states). Run the two-cup dye demonstration live if possible. W1 phenomenon worksheet as the opener; W2 vocabulary relationships to close.
2. Period 2: Lab 1, the three-cup mystery (one session). Groups score the dye spread at fixed times in three cups of unknown temperature, commit to a ranking, then reveal the temperatures with a thermometer. Follow with slides 11-14 (temperature as average motion, the spread-time bar diagram, the cold-cup discussion, motion and energy vocabulary). W5 data worksheet uses the same reasoning on a larger simulated dataset.
3. Period 3: Lab 2, the marble tray (one session). Groups shake a tilted tray of marbles at three metronome-set 'temperatures', count how many marbles reach each zone, ease off to model cooling, and count wall hits in a full and a half tray. Slides 15-16 (check on adding energy to ice, the heating curve). W3 reading passage for homework.
4. Period 4: Lab 3, the energy-token kinesthetic model (session 1: heating run and the uneven evaporation round). Groups record the model temperature after each round of tokens and plot the curve with its flat steps. Slide 17 (melting point, boiling point and sublimation as properties). W4 diagram worksheet: read a heating curve and complete particle models.
5. Period 5: Slides 18-21 (the Mount Whitney boiling-point connection, pressure from collisions, the gas-to-liquid piston panels, the syringe check). W7 misconception repair. Optional Lab 3 session 2: run the cooling sequence and compare curves.
6. Period 6: Slides 22-25 (reading water's state diagram, the prediction task with water, gallium and carbon dioxide, the dry-ice fog discussion, standard temperature and pressure). W8 collaborative evidence sort and W9 transfer problem.
7. Period 7: Slides 26-28 (misconception, synthesis, exit ticket). W6 CER as the written assessment, then W10 mastery as the quiz.

Materials overview: No open flames, and no water above 50 °C in any hands-on activity; the teacher prepares and pours the warm water. Lab 1 uses clear cups, plastic pipettes, food coloring, a thermometer, refrigerator water and warm tap water. Lab 2 uses 36 matching marbles (or dried lima beans), a rimmed tray tilted on a book, masking tape, a cardboard divider and a metronome app. Lab 3 uses masking tape on the floor, four paper cups and about fifty paper clips per group as energy tokens. The dye demonstration for the phenomenon needs two clear cups, one cold and one warm, and a white sheet of paper behind them.

• Multilingual learners: Pair each of the three states with a gesture (fists together and trembling for solid; palms sliding over each other for liquid; hands flying apart for gas) and use the gestures on every slide; provide a bilingual word card for solid, liquid, gas, temperature, pressure and melting; let Lab 1 observations be called out orally while a partner writes.
• Students who need more support: Tape a picture strip of the five Lab 1 spread scores beside the cups, give Lab 3 a pre-filled 'tokens added so far' column, provide a three-panel drawing frame with particle circles already printed for W4, and offer a sentence frame for the CER ('When ___ is cooled to ___ °C at ___ kPa, its particles ___, so it becomes a ___').
• Students ready for extension: Ask them to explain why ice floats using the particle model (water is unusual: its solid is less dense than its liquid), to find the boiling point of water at the elevation of a California town using a pressure table, or to rewrite the Lab 3 rule card so the boiling plateau is longer than the melting plateau, as it is for real water, run it, and compare their curve with the class curve.
• Students who need movement or alternative output: Lab 3 is built for movement; let the same students present their W6 reasoning as a 60-second recorded explanation while acting out the three states, and accept a labeled photo of their marble tray in place of the Lab 2 drawing.
• Students with low vision or limited fine-motor control: Use large, high-contrast cups and dark blue dye in Lab 1 with a white card behind each cup; provide large marbles or wooden beads and a tray with a high rim in Lab 2; let a partner handle timing while the student calls the spread score; offer a tactile heating curve made of a string glued to card.

• Temperature and particle motion: the lesson text (pp. 301-303) links temperature to state but never says what temperature measures. Teach that temperature is a measure of the average kinetic energy of the particles, so at a higher temperature particles move faster on average; a sample at one temperature still contains slower and faster particles. No energy calculations are asked anywhere in the chapter.
• Changes of state and the flat steps: while a pure substance melts or boils at constant pressure, its temperature holds steady even though thermal energy is still being added; the energy goes into loosening or separating the particles rather than speeding them up. The textbook does not show this heating curve, but it is part of the MS-PS1-4 model, so the deck (slide 16) and Lab 3 include it qualitatively.
• Heating-curve proportions: real water needs nearly seven times as much energy to boil a sample as to melt it, so its boiling plateau is far longer than its melting plateau (the deck's idealized curve on slide 16 shows this). Lab 3 deliberately gives both changes the same number of tokens to keep the model simple, and says so in its limitations; no task asks for the energy values.
• Fog is not gas: the opener (pp. 296-297) calls the cloud over dry ice 'smoky vapor', and Figures 5B and 6B and the Key Science Concept (pp. 303, 305, 306) draw gases as white clouds. Carbon dioxide gas and water vapor are invisible. The white cloud is tiny liquid water droplets condensed from the air by the cold gas; the book's own Figure 3 caption (p. 300) says this for steam.
• 'All substances have a specific melting point' (p. 301): sharp melting and boiling points belong to pure substances, and only at a stated pressure, as the book itself says on p. 303. Glass, wax, butter and most mixtures soften over a range of temperatures. Every prediction task in this chapter names the substance as pure and states the pressure.
• Solids and 'fixed' volume (p. 298): the book says an ice cube's molecules can neither spread apart nor move closer. Solids and liquids expand slightly when warmed because their particles vibrate harder and sit a little farther apart on average; the particles themselves never grow. Say 'nearly fixed volume'.
• Liquid versus solid spacing: the deck's particle panels draw the liquid slightly looser than the solid, which is true for most substances, but water is the famous exception: ice is less dense than liquid water, which is why ice floats. Do not teach 'solids are always denser than their liquids'.
• Inconsistent numbers in the book: the text gives 50 kPa where Figure 5B shows 52 kPa (p. 303); Figure 5A labels 62 kPa and 98 kPa while the text uses about 101 kPa at sea level (p. 302); p. 304 puts the mountain cabin at 62 kPa and then works the example at 80 kPa; and water's boiling point at 80 kPa is about 93.5 °C, so the book's point (95 °C, 80 kPa) sits barely inside the gas region. This chapter uses reference values (water boils at about 81 °C at 50 kPa, 100 °C at 101 kPa and 120 °C at 200 kPa) and keeps every state prediction at least 10 °C from a boundary. The one deliberate exception is W9, where a phase-change pack is chosen because its melting point sits inside the 2-8 °C vaccine range; there the margins are a few degrees, and the teacher notes say so.
• Water at STP (p. 307): the book says water is a solid at standard temperature and pressure, but STP's 0 °C is water's melting point, a boundary where ice and liquid water coexist. Teach STP as 0 °C and 100 kPa, which is the current IUPAC value (many references still use the older 101.325 kPa), and do not ask for water's state at a boundary temperature.
• Gallium: the photo caption (p. 305) gives a melting point of 29.78 °C; the reference value is 29.76 °C. Say 'about 30 °C at sea-level pressure' and never assess the decimals.
• Carbon dioxide: it sublimates at −78.5 °C at 101 kPa and cannot be a liquid below about 518 kPa, so 'you have never seen liquid carbon dioxide' (p. 305) is true at ordinary pressures only; fire extinguishers and some tanks do hold liquid carbon dioxide under high pressure.
• Analogies have limits (pp. 299-300): sand grains are tiny solids, and a racquetball slows down and stops, while gas particles in a container at a steady temperature keep the same average speed. Lab 2's marbles also stop when the shaking stops; name this limit with students.
• Dye spreading in Lab 1 is not pure diffusion: the dye drop is slightly denser than water and sinks, and small temperature differences set up currents that carry color. Faster particle motion at higher temperature is still the main reason the warm cup mixes sooner, but call the observation 'spreading' rather than 'diffusion alone'.
• Pressure vocabulary: the book's kilopascal definition (1 kPa = 1,000 N/m²) and sea-level value (about 101 kPa) are correct. Keep the 'more collisions per area means more pressure' explanation; do not introduce gas laws or formulas.