homeschooling,  science

doing science – measuring grapes and a new twist on homemade model volcanoes

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A tray full of grapes in corn syrup, salt, water and oil, left sitting for a few days so we could measure the change.We have two different types of science activities here. Some days our experiments are carefully planned out. A while ago we weighed individual grapes and then placed them in different environments – some in corn syrup, some in salt, some in water, some with oil rubbed on them. We waited two days and then weighed them all again (each grape is individually labelled so we could compare weight changes). We could then discuss what the potential flaws in our experiment are (in this case we weighed all the grapes but we didn’t preselect matching sized grapes, so they do have different surface areas, and a few might have other blemishes) and design another experiment to correct those flaws (perhaps using a larger number of pre-selected grapes to try to minimize the effect the variations in the grapes have on the results.) I get the kids to do the careful measuring because I want them to practice using the scale, recording results and analysing data.

Then there are other days when the science activities are much more laid back. A few days ago my son spent a long time throwing a lego car down the stairs and watching it bounce. He drew pictures of the different ways he saw it bounce depending on what angle it landed on the stairs. Then he asked to do other science experiments on bouncing. We talked about trying to make a wooden block bounce and we got out different supplies. We got out elastic bands to wrap blocks in, balloons, ribbon and erasers. We tested different methods of doing things, but we didn’t find ways of producing accurate measurements. We tried to come up with our own theories for why certain things worked or didn’t work, but the theories aren’t necessarily accurate. I like to think of it as inventor’s practice, with the kids having some challenge to try to design a solution for.

Today my oldest made a paper model of a volcano using yellow cardpaper for the cone and crumpled red paper for lava. Then my middle child wanted to make a volcano out of vinegar and baking soda. At first I resisted. Eventually I gave in, when my oldest suggested that instead of using a jar as our volcano, he use a card-paper cone (with a bottom duct-taped on). With a video about “tall painting” stuck in the back of my mind, I thought it would be interesting to try to record how the lava flowed. We tried first mixing paint in with the vinegar, but the paint settled to the bottom and didn’t erupt. Then we tried mixing food color with the vinegar, but it spread to fully and just dyed the whole page a consistent shade of red.

So we started talking about possibilities. We could look for a coloring that was light enough to burst up with the volcano but thick enough that it wouldn’t just soak everything. Or we could look for a different method of propelling the coloring up. We choose the later. After toying briefly with ideas involving paint-filled balloons, I got out a graduated cylinder filled it with paint and gave a boy a wooden dowel to use as a plunger. Our first try showed two beautiful red streaks flowing down the sides of the paper volcano. We added some black paint and tried again. Then we added water and green paint for a third run. After this I moved the volcano out of harms way and let the kids fingerpaint with the extra paint. I am learning to be patient with the messy end part of experiments.

Pushing a dowel into a graduated cylinder full of paint to watch as the paint flowed down.We talked about volcanic rocks. We talked about how thicker slower moving lava builds taller volcanoes. I am contemplating how we could explore the difference viscosity makes again. I am thinking we might be able to use two types of chocolate, pouring a spoonful of each melted chocolate to represent an eruption of lava, and then waiting while it hardens before pouring a second spoonful of each. After ten eruptions, what shape does the lump of chocolate take?

I might also try blow-painting, where we blow paint across paper though straws or have paint races where we pour different types of paint down a slope on different textured papers.

As we were doing this I remembered a time long ago when my oldest was only three or four years old and I had left him alone in the kitchen for a few minutes while I was busy with his younger brother. He had been playing playdough and he built a playdough volcano. Then he pulled a bag of flour out of the cupboard and carefully spooned some into the top of his volcano and blew gently across the top to have it erupt. He was very excited to show me it and luckily his enthusiasm was contagious and I didn’t freak out about the mess. Now I am contemplating how a similar thing could be used for art. Could we blow small colored objects into the air? (Maybe colored sand? Colored rice?) Could we get them to settle on glue-covered paper?

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