The Yummy Science of Baking Cookies

I've often heard how good it is for kids to bake because of the math they need to do but have you ever looked at baking from a scientific point of view? Petunia (so not her real name, you know that by now, right?) made cookies yesterday and this recipe got us wondering about what happens when you cream the butter and sugar, and why it's necessary and then from there we found out a few more new facts about baking cookies. 

Why do we cream the butter and sugar?

The recipe for Chocolate Chip Cookes from Cloud 9 Bakery we used had us cream the butter and sugar and then let it rest 3 times! It really helped to make these gluten free cookies light and fluffy but we wondered why.

The best explanation for what happens that I could find was on Paula Dean's website. She says,

"When butter and sugar are creamed together, the rough sugar crystals cut into the fat, creating air bubbles that are held in by it. These small air bubbles serve as a nuclei for leavening gases and steam. If the fat and sugar is creamed correctly, the entrapped air is more evenly dispersed around the fat leading to more even rising.

It’s important to remember that leaveners simply enlarge the air bubbles that already exist in the batter; they do not create more. A cookie or cake will rise when leaveners, such as baking soda and/or baking powder, are moistened and heated. They release carbon dioxide which gravitate to the air bubbles and expand them like very small balloons."

What else did we learn?

I stumbled on this great little animated video by Stephanie Warren. It's part of a TedEd Lesson. Have you seen that website yet? Great resource for homeschoolers! This lesson

Now take the review here and if you are still hungry for more there are also ways to Dig Deeper. 


Check out more of the You Are What You Eat series on TEDEd.

Happy Baking my scientist friends!

Experimenting with Invisible Ink

The kids and I tested 3 kinds of invisible ink today. Two of them were abysmal failures and one worked pretty well. In any case it was fun. Which of the above three ingredients do you think was the winner?

1. LEMON JUICE

Squeeze the juice from a couple lemons into a small bowl. Apply with a toothpick or small paintbrush. Let dry. Use heat to reveal message.

Note to self: use real lemons next time! That might work, but the lemon juice didn't really. It stained the paper right away, and didn't really change colour with heat applied. I'm not too sure how detailed a picture was on these two pages anyways. The lemon juice is very watery so I think it was hard for them to control where it went on the page, even with a small paintbrush.

2.  CORNSTARCH

Cook 2 TBSP cornstarch and 4 TBSP water in a small pot until it makes a gravy. Do not overcook. Let dry. Apply with a toothpick or small paintbrush. Let dry. Use a mixture of 1 part iodine to 10 parts water to reveal message.

It took more water than that before it could be mixed for me and it still wasn't 'gravy', and the results weren't stellar. Our iodine mixture may have been to blame but since it didn't work at all, I can't say what the problem was. The colour on the pages is just them painting on the iodine after.

Are you ready for the one that DID work now?

TA DA! This one you should try!

3. BAKING SODA

Mix equal parts baking soda and water. Stir vigorously, and apply with a toothpick or small paintbrush. Let dry. Use heat to reveal message.

The baking soda ink was also the most invisible once applied.

Here's an article on how invisible ink works.

Even Better DIY Silly Putty!

I came across this post on making your own silly putty and they had the same ingredients as we used to make Gak the other day except that they used 1/4 cup of cornstarch place of 1/4 cup of cold water.

What a difference!

The New and Improved Silly Putty

1/2 cup white glue
1/4 cup cornstarch
1/4 cup hot water
1/2 tsp Borax
food colouring (we used 8 drops for bright dough)

Mix 1/2 cup white glue and 1/4 cup cornstarch in a glass bowl (easier to clean, I think). Add the food colouring and mix again. 

In a separate bowl, mix 1/4 cup hot water and 1/2 tsp Borax until it is dissolved. Add it to the glue mixture and stir again. Get your hands in there and work the putty until it's no longer sticky. It takes a little longer for this step, than the Gak did, but it's worth it.

The kids really enjoyed making the Silly Putty and the Gak and trying to guess what the different ingredients would do. 

We also compared the results and this was the clear winner, although it made a bigger mess. It's really sticky at first. It's very stretchy, soft, and much warmer than the putty from the other day. Apparently if feels like chewed gum. :)

We've been having a lot of fun with this experiement and we have one more recipe to go, but it will be a little different and we'll hopefully get to it next week. 

Homemade Gak (Silly Putty) DIY

We had fun with science today. We made Gak, or Silly Putty, whatever you want to call it. It worked out pretty well. It's super easy to make, very little mess and a lot of fun. 

We tried changing the amount of Borax in the mixture to see what would happen in our quest for the perfect Gak (I'd call it Silly Putty but Gak is such a fun word ...). I'll give you the best recipe here first:

Homemade Gak 1/2 c White Glue 1/4 c cold water 1/4 c hot water 1/4 tsp Borax food colouring

Mix 1/2 cup white glue and 1/4 cup of water together in a glass bowl, just because I think it's easier to clean the glue out of later. Next, mix 1/4 hot water separately with 1/4 tsp Borax. Then, when it's mostly dissolved, pour it into the glue mixture. You'll see it start to make the glue stringy right away. It creates a polymer chain, meaning that the molecules in the glue stick together.

It immediately starts to separate and get stringy.

Mix it around until most of the water is absorbed, then take it out of the bowl and keep squishing and squeezing it by hand. The longer you play with it, the drier it gets. To a point, anyways.

The first batch we made was the purple one. I didn't want to have a food colouring mess so we only added one drop. Not enough. It turned out very pale. We also started with 1/2 tsp of Borax. That wasn't bad, but it wasn't as stretchy and nice as the green batch in the end.

The second batch we made was the blue one. We used 4 drops of food colouring and that made a nice bright colour. I asked the kids whether we should add more or less Borax and they agreed that more would make it more like store bought silly putty so we added 1 tsp of Borax. It did make it stiffer and hold it's shape better, but it breaks much more easily.

Batch number three was green, and it was the best by far. Only 1/4 tsp of Borax made it much more malleable and stretchy. We added about 8 drops of food colouring because the green seemed to need it. It's nice and bright.

They are all fun to play with. The blue can still be made to stretch out quite a bit, as you can see. . .

It really was quick and easy and well worth the play time we're getting out of it. We've got another recipe to test out, hopefully tomorrow. We'll keep you posted! Ha ha, blogger joke. Get it?