Relative formular — Simulation Description
Relative Formula Mass Simulation — Description & Class Activity
What the simulation does
Students build molecules atom by atom by clicking element tiles on the left panel. Each atom appears as a coloured 3D sphere in the builder area. The balance scale tilts in real time as the molecule gets heavier, giving an instant visual sense of relative mass. When a named molecule is completed (water, glucose, salt, etc.) a confetti burst fires and a fact card reveals the molecule’s real-world significance.
The right panel runs a scaffolded guided calculation: one element at a time is spotlighted — its tile pulses on the periodic table — and students are asked to recall the Ar before it is revealed. Each subtotal builds up visually until a final quiz prompt asks for the total Mᵣ before the answer is shown.
Suggested Class Activity — “Build It, Prove It”
Level: AQA GCSE Chemistry, Year 10–11 Time: 20–25 minutes Setup: Simulation projected on screen; students have mini-whiteboards or printed answer frames
Phase 1 — Whole-class hook (5 min)
Load NaCl using the preset. Ask the class: “A toxic metal and a poisonous gas walk into a reaction — what do they make?” Let the fact card reveal the answer. Repeat with glucose (C₆H₁₂O₆) and ask students to guess the Mᵣ on their whiteboards before clicking Reveal. The balance scale tilting from near-zero to a heavy lean creates a memorable anchor for what relative mass actually means.
Phase 2 — Guided practice (10 min)
Call three students up to the board in turn. Each student:
- Clicks the elements to build an assigned molecule (H₂O, CO₂, CaCO₃)
- Works through the scaffolded steps on the right panel aloud — the class calls out each Ar before the Reveal button is pressed
- The rest of the class writes the final Mᵣ on their whiteboards and holds up before the answer is shown
The pulsing tile directing attention to the correct element is especially useful here — it keeps lower-attaining students and those with attention difficulties anchored to the right part of the screen.
Phase 3 — Independent challenge (8 min)
Students work in pairs at devices (or teacher advances through each molecule on the projector with a 90-second timer). Challenge sheet or verbal prompt:
Without using the Reveal button, calculate the Mᵣ for H₂SO₄ and C₆H₁₂O₆. Show full working. Then check using the simulation.
Early finishers can build a molecule of their choice, screenshot the working-out panel, and write one sentence explaining why knowing Mᵣ matters (link to moles, percentage composition, or titration depending on where they are in the scheme).
SEND adaptations in use during this activity
| Need | Setting |
|---|---|
| Visual stress / Irlen | Yellow or peach overlay via Adaptations modal |
| Attention / tracking | Reading ruler on — follows the teacher’s cursor on the projected screen |
| Processing speed | Guided steps allow unlimited time before each Reveal; no auto-advance |
| Low literacy | Molecule fact cards use short sentences; atom symbols + colours reduce reading load |
| Projector legibility | Projector mode enabled — all text and atoms scale up for back-of-room visibility |
| Dyslexia | Dyslexia spacing on in the modal increases line and letter spacing throughout |