I also approached each skill as a problem that needed to be solved, and did it in as realistic an environment as I could. I had the scouts brainstorming through how to solve each problem (signalling, shelter building, water purification, etc) and think about what things had to be considered (environmental conditions, materials at hand, threats, etc.) and then introduced new tools and materials and let them incorporate these into their problem solving. This seems to stick in their minds better. it also is generally good to teach problem solving as often as possible. Don't be too ready with a solution for them, and let them try bad options and fail, then show them exactly why it didn't work. It depends on how much time you have though.

Go to a pharmacy (Walgreens, Riteaid, CVS) and look around, there is much there that is inexpensive and valuable for survival. Cotton balls, petroleum jelly, cordage (I like unwaxed dental floss, it is compact and you get 100 yards, it is also pretty strong).

Then go to a hardware store. Get a box of contractor garbage bags, a bright color if you can find them. They are cheap, strong and make a great shelter or poncho to preserve their body temperature. Hacksaw blades are great for small cutting jobs such as building a shelter, and you can cut one into three or four separate tools. They can also be sharpened on the flat side to make an improvised knife. There are any number of inexpensive flashlights there. Also lots of cordage for cheap.

If your garbage bags are not a bright color for signalling, go to a store that sells fabric and find a nice cotton material in a bright color. A light material can provide a sizable signal panel in a compact package. Buying in bulk reduces the price in many cases.

I also reinforce the 10 essentials, and being properly dressed for the outing. Being properly dressed is what will save their life in most cases. If they have their 10 essentials, they have most of the material they need for survival, and this is just good reinforcement. You can also have them empty their pockets and see how useful the items may be, I am always surprised what you find in some of their pockets! Also reiterate planning and leaving a plan with someone. This is what they should be doing all the time anyway, even on a car trip with their families. someone should know where they are going and when they should be there.

I brought out some other items that can be found sometimes in a survival situation, such as a broken car mirror, compact discs, extraneous bits of cloth, rubber bands, wire, plastic grocery bags, clear garbage bags, a sheet of tyvek, and other items. This is just to get them thinking of how to use materials they find around. You can introduce these in their problem solving for whichever priority you are working on. this helps them to think more creatively in solving the problem and not to stop when they do not have the "proper" equipment.