Submitted by:Beckianne D. Kilkenny,Cornelius Elementary School;
Endorsed by: These lesson plans are the result of the work of the teachers who have attended the Columbia Education Center's Summer Workshop. CEC is a consortium of teacher from 14 western states dedicated to improving the quality of education in the rural, western, United States, and particularly the quality of math and science Education. CEC uses Big Sky Telegraph as the hub of their telecommunications network that allows the participating teachers to stay in contact with their trainers and peers that they have met at the Workshops.
Date: May 1994
GRADE LEVEL/SUBJECT: 3rd & up.
This activity is the product of consistent requests received on Family Science evaluations for donuts to be served at the classes! Since we had done one entire evening class sorting, classifying and constructing dichotomous keys, it became a natural review and culmination activity for our Family Science program. It's also a big hit in the classroom!
This is the clearest and easiest road to understanding construction of a dichotomous Key that I have found.
OBJECTIVE(s): Learners will:
1.) Identify properties of donuts.
2.) Use properties to distinguish donut similarities and differences.
3.) Construct a Key that places every donut in its own category according to its properties.
4.) Identify each donut according to the Key.
5.) Eat their donuts!
1.) Knowledge of properties.
2.) Exposure to dichotomous keys and how they are used is a good idea!
6 distinctly different donuts (for a group of 6 learners)
6 sandwich bags
1 blank dichotomous sheet per person
ACTIVITIES AND PROCEDURES:
Put each donut in its own baggie.
Prepare the ditto.
Briefly review what a property is. Hold up one donut and orally list properties that might pertain such as shape, size, color, coating, etc.
Have each person pick a donut and put their name on the baggie in a permanent felt pen. Then have the group lay all the donuts out in front of them and name one property they can use to divide the donuts into two piles.
For the sake of clarity make one pile 'that which has the property' and the other one 'that which doesn't'. For example in this group of donuts :
|Bismark||Raised choc.||Raised Sugar||Cruller|
File in 1A and 1B on the dichotomous key as:
1A not round
Next take either group and divide it again by one property. For example take the not round into twist or no twist. Fill in 2A and 2B on the dichotomous key:
2A not round twist (Shirley's)
2B not round not twist(Michael's)
As soon as you've gone as far as necessary to identify an individual donut then name whose it is.
Continue until all donuts have their own individual category. Learners must name all the characteristics to "key out" their donut before they can have it to eat. The key might look like this:
|1A not round||1B round|
|2B not twist|
|3A no holes|
|4A choc.ice||4B not choc.ice|
|5A ruffled 5B not ruffled|
** Note **
Any property may be used to make each new classification. There are many right answers as long as each division is made according to just one property and states it in terms of that property; for instance:
TYING IT ALL TOGETHER:
Family Science available form N.W. Equals Portland, OR has a good unit on constructing and understanding dichotomous keys.
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