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Activity

Scone chemistry

Summary: 
Students make individual soda bread "scones". While the scones are baking they experiment with the ingredients, mixing them together to find out which combinations make a gas.
Science content (2016 curriculum): 
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)
Chemistry: Chemical Changes (2, 7)
Lessons activity is in: 
Materials: 

Scone ingredients (per student, or scale up for table group to make one mix together) or use the simplified lemon scone recipe attached:

  • plastic tub to mix in
  • metal spoon (stronger than plastic) for mixing
  • flour – 1/4 cup (students measure out)
  • baking powder - 1/4 teaspoon (students measure out - make sure they level off their spoon and don't add too much)
  • baking soda – 1/16 teaspoon (pinch) (students measure out or teacher distributes - don't add too much)
  • salt - 1/16 teaspoon (pinch) (students measure out or teacher distributes - don't add too much)
  • melted butter - 2 teaspoons (teacher can distribute if too messy)
  • buttermilk – 1/8 cup or 2 Tbspn (students measure out, or pour from aliquot in a Dixie cup)
  • labelled bowls for all ingredients with its measuring spoon, for each table group
  • oven or toaster oven to fit all scones, with baking tray
  • aluminum foil square for each student
  • sharpie to add names to foil

Scone ingredient experimentation (a set for each table group):

  • same ingredient tubs on tables, but omit messy ones if desired. I use flour, baking powder, baking soda, salt, buttermilk and also give them water. Note: warm the butttermilk slightly, so that a chemical reaction between it and the baking soda is evident
  • ice cube or small paint tray - one for each student
  • coffee stir sticks
  • waste pot - use used mixing tub
  • optional: worksheets, attached or modify for younger students
Procedure: 

Do you ever cook or help to cook at home? There is a lot of science in cooking - all that mixing and heating - lots of chemistry and chemical changes going on. We’ll make scones today and investigate the chemistry happening in our recipe. And then we get to eat our experiment!

Recipe for scones on the board:

Buttermilk scones:
1/4 cup flour
1/4 teaspoon baking powder
1/16 teaspoon (pinch) baking soda
1/16 teaspoon (pinch) salt
2 teaspoons melted butter
1/8 cup buttermilk
Mix into a ball
Bake at 450F for 15-20 mins til brown

Each student adds the dry ingredients to the tub and mixes them together. Then add the wet ingredients and mix in with the spoon.
Pick up with the hands and mix more before moulding into a ball. Put on a piece of foil.
Teacher adds their name to the foil, before putting on the baking tray and bake in the oven.

While the scones are baking:
Tell students that in the oven the ingredients are mixing together and heating up, to make a cooked scone.
Some of these ingredients have a chemical reaction with each other to make something new, a gas. The gas pushes the dough up to make it rise.
To figure out which ingredients are making a gas, we need to know what that looks like (bubbles).
I have a challenge for you. Figure out which of these ingredients are making the gas by looking for bubbles when you mix them together. Use the wells of the paint tray for trying different combinations of ingredients. (Remind students to avoid contamination by using a new coffee stir stick to pick up and mix the ingredients for each trial.)
Add water as an ingredient to try mixing, as it is a component of the buttermilk.
Optional, but recommended: students to fill out the worksheet (attached; modify for younger students) so they can remember which combinations made the gas. Younger students can draw what they find.
If students are mixing many ingredients together each time, prompt them to only mix two ingredients, so that they can figure out which ingredients alone are needed to make gas.

Results should show these results with the fewest ingredients: the baking powder and water makes gas; the (warmed) buttermilk and baking soda make a gas (though less obvious).

If time with older students: the chemical reaction happening can be shown with molecule modeals (see resource for purchase of molecule models).
H (loose hydrogen atom, present in sour things) + HCO3 (baking soda) ---> H2O (water) + CO2 (carbon dioxide gas)

Hand out their scones.
Before they eat it, ask students to break their scone open, and look for the empty spaces, where the bubbles of gas were. The gas made by the ingredients mixing made bubbles, which got stuck in the dough and pushed it up to make it rise in the oven. Then the scone baked around them.

Notes: 

Can test other sour ingredients (ketchup, vinegar, orange juice) with baking soda and find out which ones make bubbles.

Grades taught: 
Gr K
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Teacher: 
Ingrid
Teaching site: 
General Gordon Elementary Science Club
ingridscience afterschool
JEMZ+ After school science
After School Program at Elementary schools in New York City
Activity originally developed and delivered: 

The School at Columbia After School Class