Tag Archives: Thanksgiving Science

Holiday Science: Gravy

What’s so scientific about your holiday gravy?  Isn’t gravy just, well, food?  Food we put on mashed potatoes and turkey at Thanksgiving and Christmas and Sunday and, well, pretty much any time?   How could gravy have anything to do with science?

Yummy! But science?  How in the world. . . .
Yummy! But science? How in the world. . . .

Here’s the thing, drooling holiday turkey & gravy lovers:  gravy-making is all about the science of starch.

Starch?  That white powdery stuff Great-Grandma used to make her handkerchiefs and your Great-Grandpa’s boxers smooth and stiff?

Yep.  Exactly.  Only in the kitchen, we use white powdery stuff made especially for use in food.  Otherwise, it’s the same stuff.

Starch is plant-based, and many people use wheat or corn-based starches to make gravy.  I like to use corn starch*, as flour (wheat-based starch, no joke!) adds its own flavor to gravy whereas corn starch does not.  Both, however, require some fancy whisking to get all the lumps out!  (If you’ve ever had to choke down lumpy gravy, you’ll appreciate the extra effort put into smooth gravy!)

A kitchen whisk makes stirring lumps out of gravy a lot easier and quicker!
A kitchen whisk makes stirring lumps out of gravy a lot easier and quicker!

What is starch, exactly?  Interesting question!  Starch is a complex carbohydrate.  To put it more simply, starch is a fancy chain of sugars – fancy, because while sugar dissolves completely in liquid, starches absorb the liquid, rather than disappearing completely in it.

If you added a heaping tablespoon of sugar – white or brown – to your skillet of hot turkey fat, it would simply disappear, completely absorbed by the liquid.  But if you added a heaping tablespoon of cornstarch or flour to that same skillet, it would start bonding with the fat and the entire contents would start to “gel.”  Add a little salt and some milk to your skillet, keep stirring, and in a few minutes, you’ll have delicious gravy, table-ready to pour right onto your mashed potatoes and turkey slices.  Without the addition of milk, your gravy would be too stiff to ladle out!

If you use flour as your starch, your gravy will be a little “stickier” than gravy made with corn starch.  Many people prefer that, and many people do not.  Your call.  If you have a gluten allergy, use corn starch – flour contains gluten.

Take a quick scientific peek at what you’re adding to your gravy:

Simple starch molecule
Simple starch molecule

You see?  I TOLD you gravy was scientific!

Especially for you cooks, here’s a simple recipe for holiday (and any other day) gravy:

In a large skillet, heat (on low) 1 cup of turkey drippings (or ham drippings, or bacon drippings, or butter), stirring constantly.  Sprinkle one heaping tablespoon of corn starch onto the drippings, still stirring constantly.  When the mixture begins to bubble, SLOWLY add milk (or water if you don’t want your gravy as rich) and still stirring constantly.  Switch out your spoon for a whisk, and begin slowly whisking the mixture.  It will start to firm up very quickly.  When it’s the right degree of firm to your taste, remove from heat and pour into a gravy boat or bowl.  Take it to the table and start eating.  Gravy should be served and eaten immediately, so it’s probably going to be the last thing set on the table before everyone dives in.  If gravy has to sit and wait, the consistency changes.  That’s scientific, too.  Look it up.

Make a big batch; gravy freezes nicely, and there’s something about turkey gravy in the spring. . . .

Don’t think it’s just wheat and corn that contain starch.  Loads of vegetables, legumes, and grains are starchy.  Potatoes,  pumpkin, sweet potatoes,  all kinds of beans, peas, rice, and tons of other foods are starchy.   Don’t try to make gravy with all of them, though.

*Yes, indeed, the same corn starch we use for our non-Newtonian liquids!  In fact, gravy IS a non-Newtonian liquid!

How to Use Popcorn to Teach Rates

by Christy McGuire, Contributor

This time of year, students’ minds are starting to drift to the upcoming Thanksgiving Holidays. Why not use popcorn to channel a little of that excitement into your classroom? Use popcorn to teach graphing, rate, and slope. Let your students eat your props, and you will quickly be one of the coolest teachers to ever discuss rates.Here is how to use popcorn to teach rates.

How to Study Seeds with Popcorn/How to Combine Thanksgiving and Science in your Elementary Classroom

The Slow Approach

Materials:

  • Popcorn
  • Paper towel
  • Small plastic bag
  • Cups of Potting Soil
  • Ruler

Last week I gave some ideas for teaching younger students about seeds using popcorn.  Corn germinates quickly and grows quickly too, which makes it a great plant to measure over a period of time. You can get a meaningful graph by measuring every day or so.

 

  1. Start having students set up corn to germinate in the window. You can expect germination to take about three days.
  2. Then plant it in a pot with soil.
  3. Have your students measure the height of the plants every day or every two days between now and Thanksgiving, and record your findings on a labeled data chart.
  4. On the last class before Thanksgiving break, you can have them graph their findings. You may want to remind them that time is the independent variable, and thus belongs on the x (across the page) axis. Height is the dependent variable and thus belongs on the y (vertical) axis.

How to Use Popcorn to Teach Rates

The Fast Approach

Materials:

  • Popcorn
  • Stop watch
  • Oil
  • Cooking Pot
  • Heat Source

(You can also use a bag of popcorn and a microwave)

Have your students get set with lined paper and their pencils. Tell them that during each twenty-second interval, they are to make a mark for each pop that they hear.
When you call time, move to the next line and make a mark for each pop. They will repeat until all the corn is popped.

  1. Put a couple tablespoons of oil in the cooking pot and about a quarter cup of popcorn. Cook on medium heat with the lid covering the pot.
  2. When you are finished, pop some more corn, and let your students enjoy while they make their data charts and graphs. Time is again the independent variable and belongs on the x (horizontal) axis.
  3. If there is interest, try repeating for differing amounts of popcorn and think about how the amounts affect your data.
How to Use Popcorn to Teach Rates
Analyzing the Data for Either Approach (or Both!)

Depending on where you are in your curriculum, there are a few different directions you can take your class after completing their graphs.

If you do both of these projects, ask students to write a paragraph comparing and contrasting the graphs.

Or, You can have your students draw tangent lines near the beginning and end of the curve. Tell them to find the slope of each and write an explanation of why the slopes are different.

Or, ask your students to add best fit lines to the graph and calculate their slopes. Students can write a paragraph in which they compare and contrast the results of the best fit line to those of the tangent line and give an opinion on which is more useful.

Or, tell students to add a third tangent line in the middle, and find that slope. Then, graph the slopes verses time.   Ask students to write a paragraph explain the meaning of this new slope.

Put popcorn on the shopping list and plan to have some fun in your class this week.

 

Christy McGuire is a trained physics teacher who loves developing new ways for students to engage with science.  While taking a break from the high school classroom, Christy rediscovered that young children are tons of fun, and can learn powerful science and math too.  Now she is attempting to cross the excitement of early childhood style learning with serious STEM study to benefit students on both ends of the learning process.    Find activities and reflections on STEM learning on her blog: www.ThrivingSTEM.com.

Take the Thanksgiving Table Trick Challenge

While the turkey is cooking and everyone is standing around waiting for the meal to start, take out a few kitchen items and entertain your guests. Make sure you practice the challenge beforehand so you can amaze and baffle your audience. Don’t forget to reveal your tricks and your science knowledge. Make your big finish the Table Trick Challenge.

The Amazing Egg Drop
The Egg Drop is a classic science demonstration that illustrates Newton’s Laws of Motion, namely inertia. The challenge sounds so simple… just get the egg into the glass of water, but there are a few obstacles. The egg is perched high above the water on a cardboard tube, and a pie plate sits between the tube and the water. Still think it’s easy? Sir Isaac Newton does.

Tablecloth Trick
The classic “whip off” the tablecloth trick is a must for any aspiring science demonstrator who wants to be amazing! This experiment is guaranteed to either bring down the house or to get you into a lot of hot water. The idea is really quite simple – yank the tablecloth out from under a beautiful place setting without destroying the meal (or the place setting). It’s easy if you take a science lesson from Sir Isaac Newton.

Toothpick Star Table Trick
Don’t take your eyes off of these “seemingly normal” toothpicks, they might just have some magic in them! Five bent toothpicks will change positions to make a five-pointed star using nothing but a little water. You’ll have all the people around the dinner table holding their breath as the toothpicks glide into place without being touched.

Straw Through Potato
Sometimes you have to stop and ask yourself, “Who comes up with this stuff?” No one ever uses a straw to eat a potato, but science nerds seem to like to find ways to poke straws through potatoes.

Ultimate Table Trick Challenge
You need to end your Table Trick extravaganza with the ultimate table trick. Should you make a soda geyser, cause eggs to fly or whip off the table cloth? Or… should you do all three in under 60 seconds to amaze your guests? For extra fun, have Uncle Larry take the challenge. Just watch the carpeting. Mom may not enjoy the geysers in the living room.

Can’t get enough table tricks? Need a few more to fill out your pre or post dinner science magic show? Follow the links to the experiments below for additional table trick experiments.