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Logic Games Sketches

Almost all puzzles are easier to solve if you have a sketch to work with. A sketch is just a simple visualization of the situation. The simpler the sketch the better; however, be as detailed as you need to be to fit the rules in. Do not try to save time by throwing down a sloppy sketch. You’ll lose that time and more trying to make sense of the mess later.

This is the second in a series of articles that discusses the TestSherpa LSAT Method for Logic Games. The series includes the following articles:

Think about a clear, clean, and simple diagram that summarizes the situation visually.

Here is the setup for the game from the last article again:

A team of researchers releases eight homing pigeons–A, B, C, D, E, F, G, and H–from various locations at the same time on the same day. Each pigeon is expected to return to the same location on different days.

From this basic setup, a complete visualization is not possible until we read the rules. We do know a few basics, however. First, we know this is a sequencing game, so we need to know the order the birds arrive. Second, we know this is a time sequence. Typically, you will draw time sequences horizontally from left to right. This is how you normally see time sequences in real life, such as a calendar. If you prefer, however, you could draw them up and down. Just make sure you are consistent in your practice, so that come test day, you know exactly what to do with your sketch.

So, to start with, you would probably draw eight simple lines, each line representing a different day that a pigeon arrives. By the way, you should get some scratch paper and actually make these sketches as we go along so you can easily refer to them during this lesson.

We can’t do much more until we read the rules.

Paraphrase the Rules For Logic Games Sketches

Next come a group of indented rules that govern the game. There are typically between two and seven rules depending on the type and complexity of the puzzle. Some rule are fairly concrete and tell you exactly what to do. Other rules are less specific or even ambiguous. These types of rules require you to combine rules and make deductions, which is the object of this section.

Your ability to paraphrase, understand, and manipulate the rules is the key to getting a high score on the Analytical Reasoning section. The questions in this section will test your ability to make deductions based on these rules.

Don’t just read each rule–it’s important that you understand the real meaning of each rule. That is why you want to paraphrase the rules in your own words. Your words are easier to remember and understand that the test maker. Plus, if you have a systematic list of rules either next to, or built into your sketch, you won’t be as likely to forget an important rule or miss an easy deduction. With that in mind, there are really only three things you can do with a rule.

  1. Add it to your sketch. This is ideal. If you can build a rule right into your sketch, it will be very easy to remember and deal with.
  2. Paraphrase it next to your sketch. Some rules don’t lend themselves easily to your sketch. That’s OK. You still need to list them in your own shorthand so you can remember and use them conveniently.
  3. Circle and return. Some rules are tricky and may not make sense until you play with the puzzle a little bit. Do this only as a last resort, but sometimes it’s best to circle the rule and move on.

Just because step 3 of the TestSherpa method is to paraphrase the rules, and step four is to make deductions, that doesn’t mean you shouldn’t make deductions at step 3 if they occur to you. Some deductions are obvious as you start putting the rules into your sketch. Don’t wait for step 4 or you might forget them. Step 4 is more about digging deeper to get the deductions you need for the test.

Here is a restatement of the introduction to this game with the rules:

A team of researchers releases eight homing pigeons–A, B, C, D, E, F, G, and H–from various locations at the same time on the same day. Each pigeon is expected to return to the same location on different days.

A arrives after D arrives.
E is the fastest pigeon and arrives 12 days after being released.
Another pigeon arrives every two days after E arrives.
H arrives after C.
F arrives six days after E arrives.
B arrives 8 days after G arrives.

Rules 1 and 4 are almost the same. A follows D, and H follows C. But that doesn’t mean A or H immediately follows D and C. Nor does it mean the two rules are necessarily related. Further, we don’t know how many days separate them. We only know that one arrives before the other. You might draw the rules next to your sketch (those eight blank lines) with ellipses to indicate that one follows the other, but we don’t know by how many days.

D… A

C… H

(Be sure to get these in the right order–they occur in a different order than the way the rule is written, a common trap on the LSAT.)

Rules 2 and 3 fit right in with our initial sketch. Rule 2 tells us not only that E is first, but gives us the day E arrives. Rule three goes on to tell us that the other birds arrive every two days. So, if E arrives on day 12, the next bird arrives on day 14, another on day 16, and so on. Rule 5 fits right in as well. F arrives six days after E. That puts F on day 18:

Logic Games Sketches

Rule 6 is a tricky rule. It says that B arrives 8 days after G arrives. We want to sketch this in a way that is consistent with our initial sketch, even though we can’t add it right to the sketch (we don’t know exactly when G arrives). Given the other rules, we can deduce that there are three other birds that arrive in between B and G. G arrives, then another in two days, then a second in four days, a third in six days, and finally B in eight days. So sketch it like this:

G _____ _____ _____ B

Making Deductions in Your Logic Games Sketches

After you paraphrase the rules, it’s time to make some simple deductions. Typically, you do this by combining rules. We combined rules earlier to get numbers for our days. Remember, if a deduction occurs to you at any time, write it down then. Don’t wait for step four or you might forget it.

Making good deductions has a number of benefits:

  1. You learn more about the system the puzzle is based on, making all the questions easier.
  2. Since the questions are based on deductions, you’ll get a couple of gimme points that are about the deductions you make.
  3. Deductions sometimes lead to other deductions, tightening up the game even further.

You make deductions by combining rules and looking for limitations based on the rules. We’ve already combined a couple rules to get our days. The only real limitation left in this game is the “G  __  __  __  B” rule. Look at the sketch we have so far, and think about why G can only fit into day 14 or day 16.

That’s a deduction we can add to our sketch, which should now look like this:

Logic Games Sketches

Now that you’ve seen tips for making logic games sketches, let’s take at Logic Games Questions.

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