Grade 8 Classroom Update – Chemistry


Week two of Chemistry is under our belts – quite literally.  One day, we poured nearly 9 cups of flour into tortillas, focaccia, and pie crust.  By noon, most of it had been eaten.  The point of the lesson was to show how gluten alters the texture of breads both by how much there is and by how much it’s worked (kneaded).   I selected an odd pie crust recipe that had two fat sources and failed to write the second one down – so, unfortunately, the crust was a little tougher than it should have been.  We also isolated gluten from different types of flour.

We spent some time looking at starch; its insolubility, how different forms burned, and how an iodine solution turns blue or purple in the presence of starch.  We saw that barley seed has starch, but no sugar, while barley sprouts have sugar, but not starch.  The structure of starch molecules was shared, then we compared and contrasted starch to cellulose and glucose.

On Wednesday, I started an oil fire and poured water into it.  The above images are of the test Chris and I ran the previous Saturday.  There was less wind for the demonstration so the flames were more of a column, which students estimated anywhere from 5 to 12 feet in height (my guess is around 8).  The water not only produced an impressive tower of flames, it also failed to extinguish the fire.  This was perfect, it gave me the opportunity to calmly walk over to the small oil fire and place a baking sheet over the top of the pot.  The flames were gone in a couple of seconds.

We also started an experiment to determine how much sugar water can dissolve and hold in suspension and looked at the chemistry and physics of popcorn.

This week we’ll look a little more at starch, explore proteins (in addition to gluten), and look at fats.

Steve Jent
Grade 8 Teacher

P.S. I was 30 feet away from the fire when I poured the water in – the students were even further back.