Ratios
updated October 23, 2022
Recorded here is my own personal collection of articles, resources, favorite links, teaching ideas, and lesson plans. It encompasses many years, from the very beginning of my experience studying and learning about Waldorf to the present time. People from all around the world visit my site and recommend it to others. Welcome!
This site records my journey. I hope my honesty is encouraging and helps break down some barriers that may prevent people from trying Waldorf methods. Because this is an ongoing site documenting my curriculum planning and ideas, some materials are more Waldorf-y than others. Please feel free to take what you like and leave the rest.
This page has helpful links and LOADS of free resources to help you plan your seventh grade year. Enjoy!
Mission Statement - Consulting Services - Lending Library
Ratios
for Class 7
Rationale
Jamie York describes Ratios as one of the most important Math themes of seventh grade.
I strongly suggest using his math books and taking his seventh grade workshop!
Jamie York's free grade 7 downloads
All of his books are on his website. You'll want
I have
also made here a list of activities for practicing Ratios & Proportions as I come across them (like Oobleck).
OOBLECK NOTES:
I used my Recipes with Wooden Stars technique to teach the
concept of Ratios, which we introduced with the Oobleck recipe, and it worked very well. Two red stars and one green.
The recipe is two parts cornstarch to one part water. All ingredients at room temperature. Heating it up ruins it. Just mix with a spoon. Precise measuring is key to your success! Oh, this concoction is super-fun and it's great for assessing students' scientific observation.
For clean up you MUST use a DRY paper towel. Clean off your hands well with the dry paper towel and throw it in the trash. Scoop the oobleck out of your bowl with a spoon and throw it in the trash.
We let our bowls sit outside and get filled with rain by mistake before we washed them and it was easy to wash it. Becca did notice, before it rained, that the stuff outside had dried out and wasn't acting like oobleck any more but if she added water she could revive it. That was a nice review on ratios. If water evaporates out, the proportion isn't kept consistent. Add more water so you get back to that two red stars and one green star... you have oobleck again.
I also would strongly suggest adding in a few dye projects and there are so
many possibilities I just went ahead and gave Natural Dyeing its own page. Enjoy!
RECIPES for RATIOS:
Oobleck
this is the absolute best way to introduce ratios
because it doesn't work if you get the ratio incorrect, but if you DO get the ratio correct it makes an amazing
Non-Newtonian Fluid! (see "Oobleck Notes" above, and "Photos and Quotes from Oobleck Play" below)
Fake Blood around the time of Halloween
this link is to a Blood Spatter Detective Lab; the blood recipe is
Chocolate Fake Blood Recipe
4 T Warm Water
4 T Corn Syrup
1 T Powdered Cocoa
1 tsp Red Food Coloring
Blend the water and cocoa together and then add the rest of the ingredients. Let the concoction sit for a while and skim the bubbles off of the top. Add a couple of drops of yellow food coloring if you're not satisfied.
You could task students with turning the whole thing into a proportion, ie.
1 part water, 1 part corn syrup, 1/4 part cocoa powder, 1/12 part food coloring
Slime - this is equal
parts water, glue, and liquid starch (add any food coloring or glitter before you put in the liquid starch)
Quicksand
The Quicksand Book
by Tomie dePaola There's an experiment in the back for making quicksand. Since quicksand is just a
ratio of sand to water, can you make quicksand then UN-quicksand it and then RE-quicksand it?
Cooking Hot Cereal - oatmeal is 1 part oatmeal to 2 parts water; oat bran is 1 part oat bran to 4 parts water
Cooking Grains - rice, millet, barley, etc.
Perfect Lemonade
and if you didn't do candy making in grade 3, go ahead and cook sugar/water to syrup, then continue cooking
and make lollipops as the sugar/water ratio changes
Cinnamon & Sugar - we like 1/2 cup sugar to 2 T cinnamon, what ratio is this?, mix up other ratios and have a bunch of toast
with butter and cinnamon sugar, which recipe is your favorite?
Mold Killer - 2 tsp tea tree essential oil to 2 cups water - calculate ratio - calculate how to reduce this recipe to a 2 oz spray bottle
and keep the proportion correct
Some Photos and Quotes from Oobleck Play
This is Science instead of Art... but it's fun.
Why is this Oobleck so weird?
It's like wax.
It's like kinetic sand.
I wonder who found this out?
It's gooey but it's hard.
I just going to cover my entire hand in this.
We're just trying a random ratio.
This is like the funnest thing ever.
Ok, a little more water. Then don't mix it.
Put your hands in. Add some more cornstarch.
It's like green alien slime.
[after the food coloring went in]
It's alien snot.
[her partner corrects her]
I JUST PUT MY HANDS IN THAT!!!
[grossed out response]
Let's put a tiny bit of salt in it. Let's see what that does.
This is like the best day ever.
[this is from my almost-15 year old]
I want to see their snot so I'll be back.
[she says, casually walking past me into the living room]
Oh, Mom, it freezes, unfreezes, freezes, unfreezes when it falls.
[if you drop it from your hand and let it fall on someone else's hand, then fall down into the bin]
"Does it react to temperature?" I ask. "It reacts to pressure," Leah explains.
[pushing down hard to make it a solid, then lifting your hands and having the whole container rise into the air with you]
the Oobleck ratio:
two parts cornstarch (yellow stars) to one part water (green star)
the girls divide up into teams and begin to measure their ingredients
after making the initial recipe, teams begin to experiment
with other combinations of cornstarch and water
adding food coloring!
somehow both teams end up making exactly the same color
yes, alien snot seems to be a pretty apt description
lifting the pan into the air over and over -- it boggles the mind how something so gooey and liquidy can also be so strong!
this is the best day ever Mom!
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