Starters, flasks, and thermometers

This question may sound silly, but humor me. I've been using growlers to make starters since, well, forever. I boil in a pot, chill said pot, then pour and pitch my yeast.

I recently bought a 5L borosillicate flask needing more headroom for bigger starters. I know many folks boil directly in the flask, and then plunge the flask in an ice bath to chill it to pitching temps.

How do you measure the wort temperature while chilling large flasks?

I use a thermapen, and the probe won't come close to reaching the wort level in the 5L flask, even with a big starter.

What I do to check mine is to pull it out of the ice bath and it the flask on a towel. Then I place my thermometer under the flask for 5 mins and then take the reading. Seems to have worked so far for me.

I like to use my kids forehead thermometer. It works great for starters since you aren't looking for an exact temp but it does take a super quick reading that is accurate enough for a starter. Temp range between 60F and 104F. http://www.amazon.com/gp/product/B000LJAEPQ/?tag=skimlinks_replacement-20

I use one of the pistol shaped infrared thermometers. I just shoot the red beam through the opening or take a reading off the side glass. I've verified the readings with a thermapen and it is accurate.

Oh, I like the infra red idea!!