Students explain reaction rate with collision theory (collisions with at least the activation energy) and use it to explain temperature, concentration, surface area and catalysts (AC9S10U07, node 5, a hinge node).
Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.
Engage and Explore 10 min · Explain 8 min · Evaluate 3 min · Typical adds 8 min, Wider about 5 min
A concept tutorial for introducing or revising the idea; it does not replace a rate practical. Set the width with ?width=minimum, typical (default) or wider.
The hinge risk is rate factors learned as separate rules. Every factor answers one question: does it change how often particles collide, how hard, or the energy needed?
Model notes: with 15 of each reactant, run times vary from run to run (often by a factor of two), as in real small-scale experiments. Use the class's runs together, or run twice at each temperature. Typical results at 300 K: 10–30 s; at 500 K: 3–5 s. The catalyst halves the activation energy for every collision.
Explaining a rate change by how often particles collide and how many have enough energy. When a student says heat makes particles want to react, ask what changed in the panel: collisions, or the share that react.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student says heat makes the particles want to react. | What changed in the panel: the number of collisions, or the share that react? | Both, but mostly the share: faster particles hit harder, so more collisions have the activation energy. |
| A student says every collision causes a reaction. | Compare the collisions and reactions numbers in the panel. | Only a few per cent react. The rest don't have enough energy. |
| A student says a catalyst adds energy. | Did the temperature change when you turned the catalyst on? | No. The catalyst lowers the energy needed instead. |
One possible solution for each task. Other correct programs are fine.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Stretch: Food in a freezer lasts months. Use collision theory to explain why, and why it still goes off eventually.
Support: Give a two-column frame for each factor: 'More collisions?' and 'More energetic collisions?'.
For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.
You are a patient science coach for a Year 10 student in Australia. Help me understand the ideas in ONE lesson only, from the lesson "Why does heat speed up reactions?". The ideas: - Collision theory — the particle basis of reaction rates: I can explain reaction rate in terms of particle collision frequency and energy, and use collision theory to predict how changing conditions will affect rate. - Rate factors — temperature, concentration, surface area and catalysts: I can explain how each of the four rate factors affects reaction rate using collision theory, and investigate one factor experimentally. What understanding looks like: - Explains that reactions require particle collisions with energy above the activation energy threshold - Predicts that increasing collision frequency or energy increases reaction rate - Identifies at least two ways to increase collision frequency or energy - Explains how each of the four rate factors affects reaction rate using collision theory - Distinguishes catalysts from reactants and explains why catalysts are not consumed - Designs or describes an investigation to test the effect of one rate factor Mistakes students often make here: - A student says heat makes the particles want to react. - A student says every collision causes a reaction. - A student says a catalyst adds energy. How to coach me (rules from the Waypoints Kit coach): - Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question. - Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit). - If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go. - If I seem to be missing the idea that comes before this one (Reaction type patterns — classifying and predicting across all three types), check it quickly, then come back. - Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back. - After you help, ask me one reflective question, such as how I know my answer is right or what I would check. - Praise my effort and method, not my ability. - You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so. - Use simple words. - Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "Why does heat speed up reactions?".
Why does crushing a tablet make it dissolve and react faster in water?
Crushing increases the surface area, so more particles are exposed and collisions happen more often.
Next: rate factors investigated in practicals (node 6).
In class: sodium thiosulfate and acid at different temperatures (the disappearing cross), or antacid tablets in water at different temperatures and as powder.