Hands-On Life Science

I have used these experiments and demonstrations with elementary school kids--mostly K through 6th grades.

Daphnia Toxicology

Reference:
"Toxicology for Middle School: The Effects of Common Substances on Daphnia", R. N. Russo and S. Parrish, J. Chem. Ed., 72, pp. 49-50, (Jan. 1995).
"A Brine Shrimp Bioassay for Measuring Toxicity and Remediation of Chemicals", Marya Lieberman, J. Chem. Ed., 76, pp. 1689-1691, (Dec. 1999).

Daphnia are small crustaceans commonly found in pond water.
They are fascinating to watch under a microscope. Caffeine caused their heartbeat to increase noticeably, and alcohol depressed it.
You can use Daphnia to test for the toxicity of common substances such as alcohol, tobacco, coffee, and over-the-counter drugs.
Our Daphnia were somewhat finicky creatures. I had to use them as soon as possible after arrival--no later than 24 hours.
See the article for full details.
Be prepared for surprises: we found tobacco to be exceptionally toxic, and alcohol (or at least red wine) definitely prolonged the lifespan of our Daphnia!

If you are doing these experiments at a school, make sure you get permission to bring alcohol, tobacco, and over-the-counter drugs on campus!

Seeds

• Trees
  • maple ("helicopter")
  • acorn
  • walnut
  • pinecone
• Fruits & Vegetables
  • apple
  • orange
  • watermelon
  • peach
  • cherry
  • grapes
  • pumpkin
  • corn
  • beans
• Other Foods
  • sesame seeds
  • poppy seeds
  • caraway seeds
  • sunflower seeds
• Flowers & Weeds
  • marigold
  • zinnia
  • nasturtium
  • dandelion
  • burrs

Maple seeds and beans are good to dissect.
Try sprouting beans in paper towels in a glass jar.
How do seeds disperse? (Wind; stick to fur and clothes; hidden by squirrels; excreted by birds)
How are seeds protected? (Hard shells, waxy coverings)

Taste & Smell

Taste

Equipment and Materials:

• salt water (salty)
• sugar in water (sweet)
• vinegar (sour)
• caffeine dissolved in water (strong tea did not work well)
• small disposable cups
• Q-Tips
• water for rinsing mouth between samples

Procedure:
Use a Q-Tip to put a small amount of each liquid (one at a time) on your tongue. Rinse your mouth with water between each test.
Are some areas of your tongue more sensitive to different tastes?
(Recent research has debunked the idea that your different areas of your tongue are more sensitive to different tastes.)
The fifth taste, umami (savory), is not represented here.

Smell

Equipment and Materials:
Prepare 20 small vials: in each vial put one of the following substances on a cotton ball or a small piece of filter paper.
Identify each vial with a number.