Monday, May 20, 2013

Searching the stream

Now that the weather is good, there is only one thing my youngest, Gwen, wants to do: Play at footbridge Park. What's not to love? Huge old trees to climb, a fun playground and the Paulinskill to explore!

Which is why she was so excited to search for macroinvertebrates as part of our recent Trout in the Classroom activity. Messy, wet fun with interesting, tiny creatures living on the banks of the stream? Sign her up!

Macroinvertabrates have no backbones, but are large enough to see with the naked eye. In a stream ecosystem many are immature insects or larvae. They serve as important food sources for larger organisms, and as a bioindicators to scientists studying the health of a stream.

Investigating macroinvertebrates shows children the amazing biodiversity lurking just under the rocks in a river, helps them understand the connections between species in an ecosystem, and is just plain fun. It also gives children the opportunity to practice their skills of observation and categorization. These are fundamental skills for the study of biology, and science in general.

First thing you'll need is a kit, like the one below.

 Here's what it includes:

  • A plastic bin -- Great for larger organisms like crayfish or minnows, as well as acting as a carry all.
  • Towels -- You know you're going to get wet, right? Plan ahead.
  • Trowels and spoons -- Perfect for digging and sifting through soil in the riverbed.
  • A fish net -- Because it's fun to catch small fish and similar creatures. Quick little buggers! Also good for sifting through debris.
  • A foam egg carton or ice cube tray, white -- Perfect to separating and temporarily storing invertebrates while you categorize them.
  • A ruler -- Helpful when trying to use a field guide to identify an organism.
  • Magnifiers -- Get up close and personal.
  • Pippettes/Eyedroppers -- to place water into your tray or collect algae samples.
  • A flashlight -- Light can be dim under trees on some riverbanks. Bring your own light.
  • A guide -- I like dichotomous keys, like this free one. These types of guides are really easy for kids to use. They're like "choose your own adventure" novels, but for science! (Make sure you put your guide in a sealed plastic bag to keep it safe in wet conditions.)
Beyond that, you just need to get out there and explore! Keep a journal. Take pictures. Get wet and muddy. Get to know what lives in the stream or pond near you. You'll be amazed at all the little creatures you never noticed before!

Once you have a good sense of what's there, you can use that information to evaluate how healthy your stream is. The number, diversity and types of creatures living there all hold clues. Many areas have citizen science programs where volunteers can help catalog macroinvertebrates, providing important information for ecologists and scientists. 

And please, be sure to put the amazing creatures back where they belong when you are done. They deserve gentle treatment and respect.

Happy hunting!

Wednesday, May 8, 2013

Teaching Genetics: Characteristics and Traits

Students are always fascinated by their heredity, but what they take from their previous generations and express today in the way they look. Naturally curious, every child I've ever met has inventoried the many ways they look like -- or unlike -- their relatives. It's part of a human's natural development to figure out his or her place in the world, and kids often use their powerful skills of observation to do this.

So teaching genetics and heredity makes sense. Sometimes an understanding of the topic comes more easily to a child than it does to adults, simply because they are paying attention more than we typically do.

Often, when people start to consider phenotype (i.e. the outward expression of our genetic traits), they look first to the obvious -- eye color, hair color, skin color, inherited disease, etc. But I think it's fun to look at somewhat odd traits that we may not even realize are genetic! It puts in perspective the amazing amount of information encoded on our DNA!

For this I really like the free activities from The University of Utah as part of their Teach.Genetics resources for teachers. Start with the Inherited Human Traits: A Quick Reference Guide. Here you'll learn that things like left and right handedness, the ability to roll your tongue, the ways you ears attach to your head and the way to fold your hands are all genetically linked. Students get such a kick looking for these traits in themselves and classmates.

The website provides a survey activity, where you can tally the results and create a bar graph based on the results. (Always fun! Literally, one of my students today shouted, "A survey? I love survives ") Or you can continue the research -- asking friends and family about the traits -- and either graph the data or create a fun family tree based on it. (The family tree is easily adapted to homeschool use, and my daughter and I plan to complete this activity at home.) I also love playing Traits Bingo using the research.

There is also Generations of Traits which is a really fun hands-on activity the shows the passing of genetic trait from grandparents down. I like it because ti makes it clear that though may share traits with others in your family, the actual genes always come from your parents. It also shows how completely random your genetic mix is. This would be a fun one to extend with a study of the probability involved with each generation.

Monday, May 6, 2013

Fun with dry ice

Let's face it, dry ice is fun. A super cold solid form of carbon dioxide, dry ice sublimates at room temperature, creating an eerie fog. Not only is dry ice great for science experiments, it's fun for parties too.

Luckily it's not that hard to get either. I have a local distributor called The Ice Factory, where I can drive right up and ask for a 30 lb. block any day of the week. You need to bring a cooler with you, or your frozen treasure won't last very long. A good pair of work gloves are needed to allow you to handle the stuff. I often ask to have it pelleted, for ease of use. But, as you'll see below, a big block of dry ice can be a lot of fun too.

So what do you do with your dry ice, once you've got it at home? I like to let kids explore the pellets alone first, observing the fog and talking about what's happening. Then we add warm water. The warmer the water, the more fog you get, because the difference in temperature affects the rate of sublimation. If you use a large clear container, kids can also see the bubbling as gas is generated. A little food coloring helps.

Then I like to add some dish soap. Suddenly everything changes, and big cloudy bubbles emerge from the container. Popping them releases the fog held inside. It's a ton of fun. Again add a bit of food coloring for added excitement.

Later, when all the dry ice is gone, the frothy, frozen soap will be left behind. It's lots of fun to play with too!

Remember how I said I like to get a big block of dry ice as well? If you use a power drill to add a wide hole to the top of the block and smaller ones to the sides, you can create a really amazing demonstration. You'll need magnesium ribbon as well.

Magnesium is a common alkaline earth metal. It's highly reactive and burns readily, producing a bright white light. Which is pretty cool all by itself, right?

When you place the magnesium ribbon in the dry ice and light it, things get dramatic. The burning magnesium can seal oxygen from the carbon dioxide in the dry ice, burning brightly without the need for other oxygen. In turn, the exothermic reaction speeds the sublimation of the dry ice, resulting in even more fog. The science is fun, but the visual is even better!

If you decide to try this at home, be sure to do it outdoors, or in a well ventilated area. And be sure to remove flammable items. This can get hot and bits of magnesium can be thrown off.