0700 How heat is generated
0701 British Thermal Unit (BTUs)
0702 Cool spots
0703 Cold floors
0704 The outdoor fire
0705 Fire comes inside
0706 The hole in the roof | 0707 Homes built with holes

0708 Fire gets contained

0709 Building a chimney

0710 Gravity furnace

0711 House air flow

0712 The fire triangle |