Step 1: Picture the birth rate and death rate as two lines on a graph over time.
At the start both lines run high and close together. Over time the death rate line drops first, opening a wide gap that makes the population line shoot up, and then the birth rate line drops too, closing the gap again at a lower level.
Step 2: Name what happens at each part of the graph.
Stage 1: both lines high, flat population. Stage 2: death rate line falls fast, birth rate line stays high, population line rises steeply. Stage 3: birth rate line also starts falling, population growth slows. Stage 4: both lines low and close together again, population line flattens at a high total.
Step 3: Add real world anchors.
Some least developed nations still sit near stage 2; India has been moving through stage 3; most of Western Europe and Japan sit in stage 4.
Final Answer:
Reading the birth and death rate curves over time gives the same four stages: high stationary, early expanding, late expanding, low stationary.$\boxed{\text{4 stages tracked by birth and death rate curves}}$