Celery & Food Coloring Experiment

It all started with the little water dropper that came in our “Colorful Inspiration” Kiwi Crate.  My 4 year-old son pleaded to open his crate, specifically because he wanted to play with his pipette.

So, we used it to mix colored water, an activity that can seemingly keep him occupied for eternity, or at least until he’s reached mixing saturation indicated by all water turning a dark-brownish purple color. We’ve done this a few times.

This time I wanted to see if we could learn about something new using the colored water, so I searched one of our favorite blogs and found a cool-looking celery experiment on TinkerLab.

When I told H we were going to do a celery experiment, he was ready to get chopping! After a bit of thought, I decided to let him cut the veggies himself. The lesson turned out to be a good one in knife safety! He was feeling like such a big boy.


Next he added food color to water and watched wide-eyed as clouds of primary colors swirled around in the clear liquid. Though a simple action, it’s a nice way to introduce the concept of density since the dye sinks to the bottom of the glass.

Now it was time to soak the celery in the dye.


And wait… So in the meantime, he mixed more colored water using the little dropper that jump-started our science project adventure.


And after about 20 minutes, we started checking out our celery.

I was attempting the best way to photograph the teeny dots of color from the end of the stalk, when H grabbed a stalk, ripped it open, and clearly exposed the inside of the celery.

After about an hour, the dye had made its way into the leafy green tops. I set it on the table so H could discover the change on his own. When he did, he was thrilled and excitedly explained to Dad, “The blue water got to the leaves because of the teeny tiny tubes sucking the water up like a straw!”

If you leave the celery in the dye overnight, the leaves get almost completely saturated by color. We were all amazed by the vibrant blue-colored leaves. In the picture below, I placed a green leaf to the lower right for comparison.

The science: When you water the soil of your plants, how does the water travel from the soil into the plant and out to the leaves? Tiny tubes (xylem) draw the water up from the roots like a straw. It works by a capillary action. The water molecules suck up inside the tiny tubes and move up and out to the leaves as if someone was sucking on the end of the tubes. The suction actually occurs as a result of water in the leaves evaporating very slowly.

Rainbow Sugar Cookies

I love doing baking projects with my boys – it’s the perfect combination of tactile play (mixing) and fine motor practice (measuring), finished off with a treat!  My son’s preschool has been doing a unit on colors and rainbows, so I decided we should try making some rainbow sugar cookies.

We both had a great time and the cookies were delicious, but I’m not sure I’ve completely tamed the inherent stickiness of a butter-based dough with this recipe. This was not entirely a bad thing since it was a chance for me to get my son to tolerate a sticky texture he’d normally resist – the promise of cookies at the end was good motivation! A shortening-based dough would be easier to work with, but if I’m putting in the effort of making cookies anyway, why not go for the good stuff?


1/2 pound (2 sticks) unsalted butter (at room temperature)
1 cup sugar (superfine if you have it, regular granulated if you don’t)
1/2 teaspoon table salt
2 eggs
2 teaspoons vanilla
2 1/2 cups all-purpose flour (plus extra for rolling out the dough)
food coloring

cookie sheet
parchment paper
plastic wrap

Unless your kid is more coordinated than mine, you’ll definitely want to gather and measure ingredients ahead of time for this one. I like putting everything in little ramekins so we can read through the recipe together and easily add and mix.

Cream the butter & sugar

Dump the softened butter, the sugar, and the salt into a large bowl, then mash with a fork until light and fluffy. This is my son’s favorite part aside from cracking the eggs, but I still usually need to help him finish as it takes some time and effort. (You could also do this in a mixer.)

Add the eggs

Next up, the best part – the eggs! This never gets old, and my boys have been known to fight over who gets to crack the next one.  You’ll need to help pick out stray shell pieces, of course.  Add the vanilla, then beat with a fork until combined (another good mixing step for small kids). Then dump the eggs into the butter and keep mixing with the fork until it’s nice and smooth.  Since you haven’t added the flour yet, there’s no danger of over-mixing, so feel free to keep on mixing as long as your kid is into it!

Mix the dough

Time to add the flour.  My son likes to spoon the flour in a bit at a time, but just dump it all in at once is fine, too.  This is the step where you don’t want to mix too much, just until the flour all combined.

Color the dough

And now the color!  Divide the dough into 4 or 5 pieces, or as many colors as you’d like to make. The dough is so sticky that kneading it on the countertop is pretty messy and difficult, so I found the best method is to put each piece into a cereal bowl and mix it there.  We had fun adding the food coloring just a drop at a time and watching the colors change. You can knead by hand or mix it with a fork. Don’t worry if it’s not perfectly combined, the cookies will still look nice.

At this point my son was losing focus so I called for a break, which turned out to be a very good idea.  The dough was getting very soft with all the mixing, so an hour or so in the fridge made it much easier to roll out into rainbows. To prevent it from drying out, wrap each color individually in plastic wrap. (You can leave it in the fridge for up to 2 days, or freeze it for up to a month.)

Make the rainbows

When you’re ready to bake, start the oven preheating to 375F and cover your baking sheet with parchment paper.  (You can bake without it, but you run a much higher risk of the cookies sticking.)  Take out the dough and get out a little flour for dusting your work surface.

To make a rainbow, pinch off four or five small pieces of dough in different colors.  Roll each piece into a little snake and arrange into a rainbow shape directly on the parchment-covered cookie sheet.  Lay each one down in an arch shape, one on top of the other, and then gently press together.  Keep your cookies at least a half inch apart.

When you have a sheet full, bake at 375F until edges are golden brown, about 6 to 8 minutes.  You’ll have better results if you bake them one sheet at a time.

When cookies are done, immediately transfer them to a cooling rack.  You can just slide the entire piece of parchment from the cookie sheet onto the rack.  When cooled, these cookies can be stored in an airtight container for a couple weeks.

Of course, your kid might have entirely different vision for his cookie, and that’s ok, too!  Happy baking!

Two Ingredient Tuesday: Shaving Cream and Food Coloring

I’ve seen shaving cream sensory tables at my daughter’s preschool and on almost all of my favorite kids’ craft blogs, but we’ve never actually tried it ourselves. When we were visiting my in-laws last week my daughter spotted a can of shaving cream in the shower and it seemed like the right time to set up our own sensory shaving cream tray. She had so much fun with this that it made me wonder why I had waited so long! It ridiculously simple to set up, my daughter was fully invested for close to an hour, and the clean-up was easy (it’s just soap, after all!).

I squirted some Foamy Shaving Cream on a cookie tray. Make sure you use the foamy kind for good results.

After playing with the shaving cream for a little while, I introduced the food coloring. My daughter likes to take things into her own hands and happily drip-dropped the food coloring into the foamy sea before mixing and swirling it up. We talked about color mixing and I took the opportunity to teach her about warm and cool colors. We talked about how red and yellow are warm like the sun, while blue and green are cool like the ocean. She picked right up on this concept and happily talked about it the rest of the day.

Eventually the shaving cream turned a lovely shade of grey, but we kept adding more cream and food coloring until we were done.

Clean up was fairly easy: I placed a piece of paper next to the pan to absorb some of the mess, and we also did this outside just in case anything needed to be hosed down.