LuduminaSP-05 · SP-U3 · Planned
Red-shift, expansion and evidence limits
Learning objectives
Explain wavelength red-shift and distance/recession evidence; relate it to Big Bang model; acknowledge dark matter/energy and observational uncertainty.
8463 §§4.8.2 / No Trilogy counterpart
DfE single-science pp.44–45 · no Combined Space section. Evidence checked 30 September–1 October 2026. Skills: WS1.1–1.3,1.6,3.5,3.7; MS2g,4a.
Explanation
Red-shift means spectral features are observed at longer wavelengths. The relation between galaxy distance and recession supports expansion and the hot dense early-universe model. Dark matter and dark energy describe different unresolved issues; evidence-led uncertainty is part of science, not proof that nothing is known.
Concepts, equations and units: Red-shift means longer observed wavelength; expansion from hot dense early state; qualitative recession–distance relation, no Hubble-law formula required.
Prediction, demonstration and game exercise
Predict, observe, explain
Compare emitted/observed line spectra and a distance–red-shift scatter plot; separate observations from interpretations.
Planned learner game exercise
Match shifted spectral lines, order galaxies by recession evidence and write a model-evaluation memo.
Independent practice
Interpret three spectra/graph cases; critique one unsupported claim and distinguish dark matter from dark energy.
Original practice example · Separate Physics
A spectral line emitted at 500 nm is observed from a distant galaxy at 550 nm. Is it red-shifted or blue-shifted?
Show working and model answer
Working / reasoning
Observed wavelength is greater: 550 > 500 nm.
Answer
Red-shifted; the example alone is not a complete proof of every cosmological model detail.
Exit check and success criteria
Two spectral comparisons correct plus a supported expansion argument and a substantive unresolved question.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Red-shift means galaxies are red coloured; Big Bang was an explosion into pre-existing empty space; uncertainty invalidates every observation.
Practical preparation
No RP; supplied astronomical datasets.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.