Tag Archives: Baking

5. How to Think Like a Scientist – Controlling the Chocolate Chip Experiment

phineas_scientist001So I learned how to make my mother’s delicious chocolate chip cookies. But after a few batches I got bored, and like a scientist, started to experiment. My mom didn’t enjoy walnuts and rarely baked with them, but I love them. I decided to change her recipe and add walnuts to my mix. Success! My roommates and I thought they tasted great (except for my friend Tony, who is allergic to nuts).

But were the cookies better than the original recipe? It was hard to know. It was hard to remember exactly how the originals tasted. So, thinking like a scientist, the next time I divided the cookie dough into two bowls and added walnuts only to one of them. I baked both batches and we did a taste test. The walnut chocolate chip cookies were clearly superior. And Tony was happy.

Talking like a scientist, the batch of original recipe cookies was the control group and the walnut batch was test group. The original ingredients are called dependent variables and the walnuts the independent variable.

The mark of a good experiment is that it is a controlled experiment with only one independent variable. You only want to change one thing at a time so you know what you are testing. The control allows you to compare the results of the change.

It is fine to do an uncontrolled experiment (like I did with my first attempt at walnut cookies). But if the results are good, it should be followed by a controlled experiment to verify them.

Scientists use uncontrolled experiments to generate ideas for new hypotheses. Hey, what if I throw in some jalapeño peppers into the cookie dough?

Fun Phineas Fact
In medical research, controlled experiments are called clinical trials. Over the years, it has been shown that the results are more accurate if the patients don’t know whether they are in the control group or the test group. We call these blinded trials.

Think about doing a soda pop taste test with your friends. Then try it again putting a blindfold on them before they drink. Blinding prevents personal opinions from altering results.

It has been found that results are even more accurate when the doctors and nurses running the experiment don’t know which group is the control. We call these double blinded trials. A double blinded controlled trial is difficult and expensive to run, but is the gold standard of medical research.

The US Food & Drug Administration requires double blinded clinical trials be run before approving new medications.

4. How to Think Like a Scientist – The Chocolate Chip Experiment

phineas_scientist001My mother baked incredibly delicious chocolate chip cookies. A few times a year she would bake a huge batch of them. Every time they tasted the same… awesome. When I left for college I asked for the recipe. I am not a cook, but, heck, I can follow directions. How hard could it be?

Lets just say that my first attempt was a disaster. Instead of soft and gooey like hers, mine were hard and crunchy like bricks. And they tasted nasty. I tried again, this time being extremely careful to follow the recipe exactly. Same result! What was I doing wrong? It was time for me to think like a scientist to figure it out.

cookieThe next time I went home, I watched my mother very carefully as she baked them. I noticed four differences from my failed attempts:

  1. A missing ingredient. Cinnamon. Just a dash. Mom just shrugged when I asked her. Cooking is so natural to her, she didn’t even think about it. And she doesn’t even look at the recipe as she bakes.
  2. Speaking of dashes. The actual quantity of “a dash” varied from almost microscopic to a heaping spoonful depending on the spice.
  3. She used real butter instead of margarine as listed on the recipe.
  4. She removed cookies quickly from the baking sheet and placed them on a plate to cool. Apparently every cook knows this, so she didn’t write it down. I left mine on the pan to cool, and they continued to cook way too long, turning into crunchy bricks.

Armed with these insights, I attempted a third batch of cookies in my college apartment. And to the relief of my roommates, success! I nailed it perfectly.

My chocolate chip experience shows the importance of repeatability. My mom’s perfect cookies weren’t a fluke or accident, she could consistently make more any time. And just as important, I was able to get the same results when I used the same ingredients in the same quantities and followed the same steps.

Experiments following the scientific method must be repeatable by you and others. First, you as a scientist should be able to run the experiment many times and get consistent results. And just as important, other people, even your un-best friend, should be able to get similar results if they follow the same steps. If it’s not repeatable, it’s not believable. And if it’s not repeatable it’s not believable. (That was a joke).

As an experimental scientist, you must write down every detail about the experiment, even details you think are irrelevant. The day and time, the weather, the type of materials used, the location, exact quantities… everything that might affect the outcome. It would be terrible to get great results and not be able to recreate the experiment later. Think of my first batch of nasty cookies.

Here is my mom’s cookie recipe!

Rita’s Chocolate Chip Cookie Recipe (with my corrections)
Chef: Rita M. Kaufman


  • 1 cup + 2 tablespoons all-purpose flour
  • 1/2 teaspoon baking soda
  • 3/4 teaspoon kosher salt
  • 1/2 cup (1 stick) butter, softened
  • 1/4 cup granulated sugar
  • 1/2 cup brown sugar
  • 1/2 teaspoon vanilla extract
  • 1 large egg
  • 1 dash (1/8 tsp) cinnamon
  • 1 cup (6-oz. pkg.) Semi-Sweet Chocolate Morsel

PREHEAT oven to 375° F.

Line a baking sheet with parchment paper and spray lightly with nonstick cooking spray. Set aside.

COMBINE flour, baking soda and salt in small bowl. With an electric mixer on medium-high, or a wooden spoon, beat butter, granulated sugar, brown sugar and vanilla extract in large mixer bowl until creamy (about 20 minutes). Add eggs. Gradually beat in flour mixture. Stir in morsels. Drop by tablespoon onto baking sheet.

BAKE for 9 to 11 minutes or until golden brown. Cool on baking sheets for 1 minutes, move cookies to a plate to cool completely before serving (about 15 minutes).

Fun Phineas Fact
Where you live may affect how you bake. My mom’s recipe was written for cooking near the ocean. If you live at a higher altitude, like Colorado, you will need to make changes to get the same results. At high altitudes, water boils quicker, cookies bake slower, and dough rises faster. Check with a local cooking expert to make adjustments for your kitchen.


Website: Betty Crocker Baking Guide

Podcast: Skeptics Guide 5×5 episode 65.