Science Smarts: The science of chocolate

By Patty Rooks on February 7, 2026.

This week has been a busy one as I visit schools helping students prepare for the upcoming Regional Science Fair on Mar. 21 at Medicine Hat College. I always tell students the most difficult part of starting their project is choosing a topic. The next thing I tell students is pick something of interest to them. Well, with the upcoming “holiday,” I thought this may be an appropriate one to choose as a first-time project. Let’s get started!

*Remember to ask an adult before doing this experiment.

Materials

– Adult science helper

– Oven

– Mixing bowls

– Mixing spoons

– Measuring spoons

– Measuring cups

– Oven mitts

– Baking pan

– All purpose flour

– Brown sugar

– Vanilla extract

– Salt

– Egg

– Chocolate chips (your favourite)

– Butter

– Milk

– Baking soda

Procedure

1. Have an adult help you turn the oven on to 190° C (375° F).

2. Measure 175 mL (3/4 cup) of butter and put into a large mixing bowl. Add 300mL (1 ¼ cups) lightly pack brown sugar. Mix until well combined and light and fluffy.

3. Beat in one egg, 30 mL (2 tablespoons) milk, and 10mL (2 teaspoons) of vanilla extract. Mix until well combined.

4. In a separate bowl measure 500 mL (2 cups) of all purpose flour. Add 5 mL (one teaspoon) of salt and 3 mL (3/4 teaspoon) of baking soda. Add to the wet ingredients and mix well.

5. Gently stir in 250 mL (one cup) of chocolate chips.

6. Drop by spoonfuls onto the baking sheet.

7. Place in the oven and bake for 10 minutes (for a chewy cookie) or 13 minutes (for a crispy cookie).

8. Allow to cool on the baking sheet for a couple of minutes before placing on a baking rack to cool.

9. Enjoy!!

What is going on?

So many things can affect a simple little chocolate chip cookie These can include: temperature, butter and sugar. After much experimenting, I have learned that for a crispy cookie, you need to use granulated sugar and butter (no substitutes).

You also have to bake the cookie for the full time indicated in the recipe. Store these in an airtight container so they stay nice and crispy. Now if you are like me, and like a chewier almost caramel tasting cookie, you MUST use brown sugar and when you measure it pack it in firmly.

When it comes to baking it, I slightly under bake it so it is still soft and chewy! There are others that like a more cake like cookie. This is an entirely different ball game, as you need to change the flour up. Use cake or pastry flour. This type of flour is made with a different type of grain (a whole other science lesson!).

This in turn affects the texture and even gluten content which affects the structure and even texture of the cookie. Oh my, I am running out of time this week, and better stop there on the science behind the ultimate chocolate chip cookie!! Stay tuned, I may investigate this further in the future!! Hmm, leaveners?

Oh, one more thing! You know this may possibly be the most delicious Science Fair project one could do. There is still time to put together your science fair project for the Regional Science Fair on Mar. 21. We are also still in need of judges for the day. If you can lend even a couple of hours, that would be greatly appreciated! Call or email Patty today for further information.

Do not forget to register for the upcoming Regional Science Fair at Medicine Hat College. The link is: https://forms.gle/YmQuZ7cEkfAtZDM99 .

Patty Rooks, senior scientific consultant Praxis Science Outreach Society. Praxis is located in the Community Futures Entre Corp Building at #202 556 Fourth St. SE, Medicine Hat, Alberta, T1A 0K8. For all your science needs, please email praxis@praxismh.ca.

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