![]() Design a short dichotomous key using a particular item (examples: coke tabs, empty ketchup bottles, paper clips, etc.) and have the students work through the key.BM 4 : Seashell Pictures for Dichotomous Key Activity - (PDF), (PDF), (PDF).BM 3 : Student Activity, Using a Dichotomous Shell Key, version 2 (PDF).BM 2 : Student Activity, Using a Dichotomous Shell Key, version 1 (PDF).BM 1 : Student Guide to Using a Dichotomous Key (PDF).If student is a visual learner use Blackline Master 3. HINT: f the student is a verbal learner use the key on Blackline Master 2. If you do not lighten the density, the images will be difficult to see. NOTE: When making copies of the seashell pictures from your blackline master, lighten the density of the copies, and if possible, use the photo/text option. It is suggested that if you use this activity many times, you should laminate the pictures of the shells and then cut them apart as sets for future use. ![]() Links to downloading the Blackline Masters can be found below.ĭuplicate as many keys and sets of seashell pictures as necessary for each student or student group. Pick one of the dichotomous key worksheets both reflect the same dichotomous process and use the same seashell pictures. In this activity you will find two styles of dichotomous keys (download Blackline Masters 2 and 3) and seashell pictures used in the keys (Blackline Master 4, pages 1-3). While this method may prove to be more difficult to construct, many users prefer it because it gives them more information.īlackline Master 1 gives students instructions on how to use a dichotomous key in general. When the dichotomous key is grouped by relationships, the choices are separated, yet it is easy to see the relationships between them. However, relationships between various characteristics are not emphasized. When the dichotomous key is set up by presenting the two choices together, it is easy to distinguish between them. One way is to present the two choices together, and the other way is to group by relationships. There are two ways to set up a dichotomous key. Knowing the difference between these two types of descriptions can be immensely beneficial for creators and users of dichotomous keys. Examples of quantitative descriptions are such phrases as “has 10 striations on top surface,” “has 8 legs,” or “weighs 5 grams”. Examples of qualitative descriptions are such phrases as “contains green striations on top surface” or “feels slick on bottom surface.” Quantitative descriptions concern values that correspond with the item being classified. Qualitative descriptions concern the physical attributes, or qualities, of the item being classified. There are two kinds of descriptions that might be presented to the user of a dichotomous key: qualitative and quantitative descriptions. If the user makes the correct choice every time, the name of the organism will be revealed at the end. In each step, the user is presented with two statements based on characteristics of the organism. “Dichotomous” means “divided into two parts.” That is why dichotomous keys always give two choices in each step. Keys consist of a series of choices that lead the user to the correct name of a given item. It is the most widely used form of classification in the biological sciences because it offers the user a quick and easy way of identifying unknown organisms. The student will use a dichotomous key to identify seashells.Ī dichotomous key is a tool that allows the user to determine the identity of items and organisms in the natural world. The students will explore the benefits of creating and using dichotomous keys as a means of identifying an organism or object. Education on the Halfshell: Understanding a Dichotomous Key
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |