Sunday, January 29, 2012

Salad Dressing

You are probably aware that oil and vinegar do not mix, but did you ever consider it that when you shake them together you are creating a liquid-on-liquid suspension?

When I first considered this lesson, I thought perhaps it was a little weak on the cooking front. (Although not as weak as the rock candy. Those wooden stirrers still don't have enough candy to eat on them.) Then I wondered if my students knew what salad dressing was made out of and decided this might be a real learning experience for them. When I introduced the lesson I was surprised that even the most food savvy of my students didn't know that oil and vinegar were the basis of many salad dressings.

We started with some vinegar in small jars, and talked about how some pairs of liquids can be mixed together, but others create a suspension and ultimately separate. Then I measured oil into each jar of vinegar and sent small groups off to shake it up and time how long it took to separate. Although I told them to give the jars 10 shakes, there was some variability from table to table as the oil and vinegar separated. Whether this was from number of shakes or vigorousness of shakes is not clear; either way kids' interest was not captured by this activity. Plus it was Friday afternoon. I decided to cut my losses and leave it at the idea that they were forming a suspension and it was the basis for a vinaigrette.

I passed out small cups full of measured seasonings, kids shook it into their jars, and voila! Salad dressing!
Add some veggies from the kitchen*, and kids were munching on a healthy end-of-the-week snack with a homemade topping.

We put the extra in our class fridge and will use it next week with the leftover veggies and the school-provided snacks that come out of the kitchen every morning.

I consider this mission accomplished. Although we did not practice the steps of the scientific method, kids did experience both a science concept and gain practical kitchen knowledge.

*When I asked Emily if we could get some leftover vegetables for this lesson, she offered a crudite platter! How lucky we are to have a kitchen manager who used to run an upscale restaurant in the area.

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