Sisters Traveling Molecules Answer Key

What This Actually Is

Sisters Traveling Molecules is a lab-based chemistry activity where students match molecular models or cards to their corresponding structures, names, and properties. The answer key exists because teachers need a reliable reference when grading or when students get stuck on tricky isomers and structural formulas. I've spent more hours than I care to admit tracking down the right key for different versions of this game, because there isn't just one standardized edition. Different publishers and school districts use slightly different sets of molecules, and the answer key you need depends entirely on which version your class is using.

Sisters Traveling Molecules Answer Key: How to Get the Right One

The first step is figuring out which version you're working with. Check the student handout or the game cards themselves. Most versions will list a unit number, a teacher guide ISBN, or a specific set of molecules like ethanol, propane, or glucose. If you don't have any of that, look at the molecular formulas on the cards and compare them against the key below. Here's the core of what most keys cover. The game typically includes molecules across four categories: hydrocarbons, oxygen-containing organic compounds, simple polymers, and amino acids. Each molecule has a structural formula, a molecular formula, a name, and sometimes a polarity label. The answer key maps each of these attributes to the correct card.

Common Molecule Reference List

Below are the most frequently tested molecules and their standard answers. If your key uses slightly different naming conventions, the structural information will still match. Methane — CH — nonpolar — simplest alkane
Ethane — CH — nonpolar — two-carbon alkane
Propane — CH — nonpolar — three-carbon alkane
Butane — CH — nonpolar — four-carbon alkane
Propene — CH — nonpolar — contains a double bond
Ethene — CH — nonpolar — simplest alkene
Hexane — CH — nonpolar — six-carbon alkane
Cyclohexane — CH — nonpolar — ring structure
Ethanol — CHOH — polar — hydroxyl group present
Propanol — CHOH — polar — three-carbon alcohol
Methanal — CHO — polar — aldehyde functional group
Propanone — CHO — polar — ketone functional group
Butanoic acid — CHO — polar — carboxylic acid group
Glucose — CHO — polar — hexose sugar, ring form
Galactose — CHO — polar — glucose isomer, different OH orientation
Fructose — CHO — polar — ketose sugar, structural isomer of glucose

When the Key Doesn't Match Your Cards

I ran into this problem last semester with a district that had modified the original game. They'd swapped out butanoic acid for pentanoic acid and added a second isomer of hexanol that wasn't in any published key. I spent about forty minutes cross-referencing the molecular models against the structural diagrams before I realized the answer key they'd distributed was from an older edition that predated their revision. The workaround was straightforward once I identified the mismatch. I pulled the student activity sheet, listed every molecule that appeared on it, drew out the structures for the ones I was unsure about, and then verified them against the structural rules rather than trusting a potentially outdated key. If you find yourself in the same situation, don't waste time searching for a "complete" key online. Build your own from first principles. Identify the functional groups. Count the carbons. Check the bonding patterns. It takes longer the first time but it's actually more useful because you understand why each answer is correct.

Pitfalls Students (and Teachers) Keep Making

The most common error is mixing up structural isomers that have the same molecular formula. Glucose, galactose, and fructose are the classic trap here. They're all CHO. The answer key will list them as separate entries because their structures differ, but students will routinely pair them incorrectly if they're only looking at the molecular formula and not the full structural diagram. Another frequent issue involves polarity classification. Some keys mark certain molecules as borderline cases. For example, propanone is polar due to the ketone group, but a six-carbon chain with just a single oxygen can behave almost nonpolar in certain contexts. The game simplifies this by treating it as polar, and the key reflects that simplification. Don't overthink it for the purpose of the activity unless you're teaching beyond the scope of the game itself. There's also a recurring problem with ring versus chain representations. Cyclohexane and hexane have very different structures despite both containing six carbons. Students will sometimes match them to the wrong card because they're focusing on the carbon count instead of the connectivity. The key will show cyclohexane as a ring and hexane as a straight chain. Make sure students are actually reading the structural diagram, not just the formula.

How Long This Usually Takes to Grade

A complete game set with twenty-five to thirty molecule cards typically takes between ten and fifteen minutes to grade using a standard answer key. If you're doing it by hand and each student is matching cards individually rather than working in groups, it can stretch to twenty minutes per class. Digital key systems that use scan-tron style answer sheets cut that down to roughly three to five minutes, but not every school has that infrastructure. If you're printing keys for a large department, consider laminating them. The physical cards get handled roughly, and the printed keys tend to develop creases and stains within a semester. A laminated key lasts through multiple years of use without the molecular formulas becoming illegible.

Where to Find Printable Versions

The most reliable sources are your textbook publisher's teacher resource portal, your district's shared drive, or educational platforms like Teachers Pay Teachers where educators upload their own formatted keys. Avoid random PDF hosts that claim to have "the complete answer key" — many of those are outdated or contain errors that propagate through multiple copies. A quick way to verify a key before using it is to check three random entries against actual molecular structures. If two out of three are wrong, the whole document is unreliable. I keep a personal backup folder with versions from the last five years because updates happen without much notice and a key that worked last year won't necessarily work this year. It's not glamorous, but it's saved me from having to reconstruct a key from scratch during a sub situation.