The Fire Triangle


The fire triangle is critical to ­fire ­fighting and fi­re investigation. Fire professionals must understand what are needs to burn and how eliminating one leg of the ­fire triangle can extinguish are. Why do ­fire ­fighters use water to put out a fi­re? What leg of the ­fire triangle are they eliminating?

Just like a candle flame can leave a soot pattern on a ceramic tile, ­fire investigators look for these types of patterns on walls, furniture, and other parts of structures to help them determine the point of origin of the ­fire, or the location where the fi­re started. Knowing where are started helps investigators understand how it was caused.


  • What are the three things a fire must have to burn?

Problem to be Solved

  • Firefighters and fire investigators need to know basic fire science to both fight fires and to uncover the source of a burn.


The Fire Triangle

Age Group

Middle School


Fire Forensics


  • Long reach lighter
  • Pillar candle or small candle
  • Metal/non-flammable pie pan or tray (not! plastic, paper, or wax coated material) – place candle in pan
  • Metal/non-flammable pie pan or tray (not! plastic, paper, or wax coated material) with 1-2″ of water
  • Aluminum foil pieces (2) 2 cm x 2 cm with small slit (1/2″) cut in the middle of one side
  • Glass jar or drinking glass
  • Small (5 cm x 5 cm) metal screen (non-flammable)
  • Tongs to handle materials that are hot or briefly flaming – plastic/heat resistant coated handles
  • Large screwdriver with plastic (non-heat conducting) handle
  • Ceramic tile
  • Xplorlabs video: Investigation 1


Using a candle, students conduct four experiments to limit one of each side of the fire triangle – oxygen, fuel, and heat - to understand the needs of fire. Then, using a metal screen, students look at a candle flame to observe combustion.