Varroa mite sugar shake test

Today was the day I did a sugar shake test in order to get a good idea of the hive's mite infestation. I had examined the beetle trap earlier this week (with Karly and Sophie) 3 days after I cleaned and replaced the tray and found 8 mites. That is an okay number.
Three days ago I paid a visit to Mountain Farm and Feed Supply in Ben Lomond. I spoke with Lauren, a beekeeper and bee keeping teacher, about mites and mite control. I bought a frame holder (mine's white) and a drone brood frame.
The weather today was partially overcast, no wind. My girls were happy and calm. No wax in the top super, just a few bees wandering about. In the middle super, there were 3-1/2 frames of brood, in a lovely pattern, and one frame full of capped honey.
Saw the queen in the brood chamber and the usual good amount of brood. I didn't see any drone cells and not a single Italian. Because of my irregular spacing with only nine frames, there was a bit of brace comb. Upon removing the middle super, a cell was broken open revealing a pupating bee. I left her for the others to take care of.
Then for the test. I had a 1 pint mason jar with a 1/8" mesh screen instead of a regular lid. (I'd had to buy a 20' roll in order to just have a few inches.) I had used 1/2 cup of dried beans to measure and mark the level. I selected two brood frames, double-checked that the queen was on neither and observed her elsewhere. Then I brushed the bees from both sides of the frame into a bucket. Most of them stayed in the bucket. Then, using the jar as a scoop, I collected 1/2 cup of bees, about 300 I read. I then put the hive back together with the green drone brood frame near the center.
Then I put in two tablespoons of powdered sugar. I had to rub the screen to get it to go through, making sure that I was rubbing where there were no bees.
I shook and rolled the jar for a couple of minutes and then waited a couple of more. Then I shook out the sugar into a bowl. Those two dark spots on the right are varroa mites.
According to one source I should double the number when the bees come from a brood frame, therefore 4 mites/ 300 bees equals only 1.3 mites/100 bees. Hurray! One needs to treat with 10/100.
The bees in the jar were buzzing angrily. I put the jar outside in the shade and gave them about 15 minutes to calm down. Then I covered up again and took them to the hive. When I opened the jar, some flew out. I then shook the jar, but not vigorously because there was a bunch of sugar stuck on the bottom. More bees came out. I blew in the jar, a few more flew out. Finally I resorted to using the handle of my bee brush to get them all out. Phew!