Turn the Bunsen burner upside down to close the needle valve underneath. Twist the knob under the burner clockwise until it's tight.
Open the gas valve by twisting the handle at the gas jet so that it aligns with the nozzle underneath.
Open the needle valve by moving it a quarter-turn counterclockwise.
Hold the flint striker at a 45-degree angle to the tip of the Bunsen burner. Squeeze the striker handles together to produce sparks. If the Bunsen burner does not ignite after three attempts, shut off the gas and wait 10 minutes for the gas to evaporate before trying again. Meanwhile, confirm that the striker produces sparks when squeezed. If it doesn't, replace the flint.