Square Dance Study Hints
Chain Reaction
1. Study the Definition
As with any call in Challenge dancing, the first important step is to understand the definition. But Chain Reaction is an interesting case because many people learn to do it at A-1 without fully understanding the definition.
Note that the definition at C-1 is not really any different from the definition at A-1. The only difference is which cases are allowed. So if you actually learned the definition of Chain Reaction when you learned A-1 then you should be in relatively good shape.
If you did not learn the definition when you learned A-1 -- or you have forgotten it -- then you are better off just treating it as a completely new call. Trying to muddle through by doing what you did at A-1 and hoping there won't be anything weird is not going to be effective. Take the time to study and memorize the definition, as if you had never done it before.
Here is Vic Ceder's definition page:
Read the definition itself, at the top, and also the notes.
2. Review the Basics
The definition will tell you what is coming up next, but how fast and accurately you can do each next part depends on how well you know those actions.
passing thru
At the beginning, the very center passes through with one of the dancers from the outside. The important points here are (1) it is always a right-shoulder pass and (2) neither of these dancers turns, as part of the pass thru. If the outside dancer was a beau, then he or she will still have his/her right hand into the center of the set, forming part of a right-handed star. If the outside dancer was a belle, then he or she will still have his/her left hand into the center, forming part of a left-handed star. You don't need to remember these two possibilities separately -- just walk straight forward without turning and the correct thing will happen.
hinge
Make sure you really understand Partner Hinge. Note specifically that Partner Hinge always leaves the dancers holding right hands. This means that they will be holding right hands after the hinge either if they find themselves meeting with right hands before the hinge or if they find themselves meeting as a couple. They will have left hands after the hinge only if they actually meet with left hands before doing the hinge.
trade
Make sure you really understand Partner Trade. Note specifically that in a Partner Trade, as with any sort of trade, both dancers turn around halfway. Whichever way you come into the trade, you must turn around and face the other way as part of the trade. If both dancers start facing, together, the same way, then they will both turn around to face the other way. It's OK if they are a couple, both before and after -- do not try to "fix" it to have the dancers facing opposite directions.
star
In some cases the "star" will be "facing". If it seems too weird to visualize a star turning both ways at the same time, then you don't need to think of it as a "turning" object at all. You can instead consider the action to be a circulate to the next spot among those four spots -- just like a Diamond Circulate, except that everybody is close together. You pass right shoulders, just as you would for a Diamond Circulate in a facing diamond, or for a Box Circulate from facing couples. Or, you can think about it as each dancer in the star doing a Counter Rotate 1/4 -- again passing right shoulders as necessary just to avoid the collision. However you want to think about it is fine, as long as you somehow get the idea that you need to move to the next spot, keeping the same shoulder toward the center.
cast
Make sure you really understand Cast Off 3/4. In particular note that if you find yourselves as a couple, you must turn as a couple away from the center of the set.
3. Explore the Possibilities
You can use the Taminations page to explore the possibilities. There are six different starting formations that lead to one or more of the "difficult" versions of the basic actions. For each of those formations, you could start in any one of four positions. (These positions are represented in the animations by the head boy, head girl, side boy, and side girl -- but in actual dancing you could be in any of these positions.) Use the manual scrolling feature of the Taminations page to run through each of these 24 possibilities and watch what happens to you.
The point of doing this is not to attempt to memorize all these possibilities. It is, rather, to help you get used to the idea that running into a Partner Hinge, a Partner Trade, a facing star, or a "push cast" is a perfectly normal thing. You should not consider it surprising, and you should not try to "fix" anything to avoid doing it.