Subject Area Lessons

## #678. Amazing Apples

Science, level: all
Posted Wed Sep 30 10:20:09 PDT 2009 by Bfly Donna (Bfly Donna).
Butterfly House, St. Louis, MO

These are idea starters collected from science center educators from across the country.

fruit batteries...btw, don't google "apple battery" it will be useless. Instead, try "fruit battery apple"

How about an activity based around how Newton's discovery that gravity extended to the moon was inspired by an apple falling from a tree? Maybe an
activity with ratios or the "do two objects of different size fall at the same rate" experiment.

Poke a hole through the center of a peeled apple with a knitting needle and pull some yarn through w/ a crochet needle. The kids carved out faces with a plastic knife and stuck beads, pipe cleaners and yarn in the dug-outs. As the apple dries it shrinks and holds the ornaments. Tips: Don't do it on a carpeted area and you need to get a good apple peeler!

Cut apples different ways and talk symmetry

I grew up on an orchard and consider myself a bit of an apple coinsurer. So here are some ideas from a kid in the know:

Have a bowl of cut apples in acidulated water (water with lemon juice) and compare them to apples in a bowl to show how the fruit oxidizes and turns brown.

Use a refractometer to measure the sugar content of different varieties. Do taste tests to see if they match up with the measurements.

Measure the PH of the juice of different varieties. (it may not that be that different but my guess is that the more tart the juice the lower the Ph.)

Use a cutting strain gauge from the food industry to measure crunchiness.
(There is an excellent episode of Mythbusters where they used one on steaks tenderized with explosives.)

Weigh apples whole and then weigh the pulp after putting it through a juicer to measure the percentage of water. Try with different varieties. Give kids the juice. Have them guess the weight difference.

Do a taste test of apples that are very cold versus apples that are close to room temp. (Ice-cream and sodas have tons of sugar because our taste buds have a harder time sensing sweet when they are cold.) This is one of the reasons that an apple right off the tree often tastes much better than one out of the fridge.

Do paper chromotography with the pigments in the peels. I am not sure what you have to use to extract the pigments. I would try water, alcohol, and possibly acetone. (I have never done this with apples it is worth testing but is has lame-tential.)

Do a DNA comparison of different varieties. See if you can see which varieties are most closely related.

Each apple blossom can make up to 5 apples. Orchardists thin all but one of the apples from each blossom to get one big one rather than 5
mini apples. This used to be done by hand but now they have spray on plant hormones that do it for you. You could have pics or samples of apples that were and weren't thinned.

Show examples of grafting. Often the roots of a tree are a completely different variety than the fruiting part on top.

Have a varietal display. With a little calling around you should be able to get your hands on more than 15 or 20 different varieties. Honeycrisp (U of MN developed this one.) Sweet and super crispy - almost
like eating a really tasty jicima
Fuji- Sweet and tasty
Gala - Like candy
Pink Lady - a lot like a honey crisp
Macintosh - tart and crunchy
Jazz - Kind of Spicy yeeha!
Cortland - thick skin and a bit mealy
Braeburn (The skin is thicker than leather and always gets in my teeth ew!)
Red Delicious - the Lowest common denomenator of apples. A perfectly ripe one right off the tree is OK but that is about it. They get mealy really
fast.

Two apples and some string can make a great coupled pendulum exhibit. Tie about a meter of string horizontally between the backs of two chairs. Hang two apples from this, tied by their stalks, dangling just above the floor on two more exactly equal lengths of string, about, say, thirty three centimeters apart. Set one apple swinging. Watch it slow down and stop as the other apple starts to swing. Then watch the second apple slow down and stop as the first apple ............

Throughout this dance, the total energy of the two apples remains constant.

In days gone by, when people used just a sharp knife to peel apples, it was a common breakfast table challenge to get the peel off as one continuous strip with a ring at each end - and no peel left on the apple.

This is rather off-topic, but apples often remind me (I am a geologist) that, if you blew an apple up to the size of the Earth,
the skin in thickness would represent all the crust, oceans, tectonic plates etc. and most of the atmosphere - everything that we know directly, and that is above the Mohorovicic discontinuity. It's a useful scale reminder, but otherwise irrelevant to apples.

How about comparing the eating/cooking properties of various apple varieties? From looking at the skin, internal texture.... can you predict what will be good to eat out of hand, what to make apple sauce (personal recommendation: Lodi apples), what to make apple pie, what to make cider?

And then there's comparing apples and oranges...

Different varieties of apples oxidize at different rates. Is that due to a difference in the Ph level? that could be an interesting test.

If you need to peel a lot of apples, I bought a great apple peeler at one of those chain stores (Bed Bath & Beyond, or the other one, don't remember which). It was <\$25 and works far better than the much more expensive one I tried. It's the old fashioned peeler, place the apple on
the prongs, turn the crank & it peels, cores and slices. I think you can disengage the slicing blade. Kids love to turn the crank. They are rewarded with a (usually continuous) string of peel and a spiral of sliced apple.

And for a little background on the fascinating history of apple propagation and Johnny Appleseed, read the chapter on Apples in Michael Pollen's book, The Botany of Desire.