Blackworm Lab for Beginning the Year
From Charlie Drewes Website (click to go there)
Here’s my favorite lab for the beginning of the year: Blackworm Lab
I modified information and labs from the iconic Charlie Drewes, formerly of Iowa State University, and Randy Dix of Olathe North High School and gave it a special twist I learned from Sandy Collins of West Junior High in Lawrence. For further information on Lumbriculus variegatus you can visit Charlie Drewes’ website which is still being maintained at the university and is a treasure trove of labs and activities with invertebrates.
From Charlie's web site (click to go there)
Sandy’s idea that I love has students creating labs and experimenting with organisms they believe are being exposed to stimulants and depressants. After they have all completed the lab you tell them that although the water containers were labeled differently, there was no actual difference in the water. I find we can then launch into rich discussions of the reasons for blind and double blind studies AND how some of the greatest discoveries have come about when scientists got unexpected results and strove to understand and uncover what had really happened.
I also find that during the lab some students get data they believe to be wrong (no difference in pulse rates between the groups). They come to me and ask what is wrong – I use the opportunity to ask them if they were very careful in their technique, if they assure me they were I tell them they should trust their data and try to understand it. It’s fun to have students who think they’re getting poor data get rewarded in the long run with praise for having the most accurate results. (I also give a 5 pt bonus for getting good results and recognizing them.)
Eric,
No, I don’t collect my own worms because so far as I know they aren’t found in our local ponds and lakes (I think the water is too warm). Lake Okoboji in Iowa is the closest place I know for sure has them. So I just order a small batch, Carolina is a source, sometimes pet stores have some live ones (for fish food). Once you have them you can keep them pretty easily for lots of activities, including student research. Charlie’s site has lots of info about additional activities, worm care, etc.
Paula,
So do you collect the worms that you use from ponds around cattails? or does Carolina or other biological supply companies sell this particular species? If you do the field collecting, could you describe your technique?