# Recognizing When Radical Expressions are Undefined

##### This Recognizing When Radical Expressions are Undefined video also includes:

Many times budding algebrists are fine when plugging specific numbers into expressions, but less certain when the range of acceptable values is undetermined. This detailed presentation helps the class move from the point value to the entire solution set when checking the discriminant radical expression. Problems are worked step by step with thorough explanation and slowly escalate from the easy plug-ins to the harder solution sets. This lesson makes an excellent way to introduce the topic or for remediation when working on teaching quadratic equations.

CCSS: Designed
##### Instructional Ideas
• Linking presentation on a class website would allow learners to work the lesson before class, in a flipped classroom model, or access homework help in a traditional setting
• Assign each pupil a number, and have them work problems to find which x's make a particular radical expression undefined. Then they group themselves by what kind of answer results from their value of x
• Leave with a corresponding problem set from your curriculum as a substitute lesson plan
##### Classroom Considerations
• Lesson viewing requires Internet access
• Some curriculum might require interpretation of results as imaginary, instead of undefined
• Consider pausing the video as each problem is introduced to allow time for seatwork and questions
• Presentation assumes learners are already familiar with the term discriminant.
• This resource is only available on an unencrypted HTTP website. It should be fine for general use, but don’t use it to share any personally identifiable information
##### Pros
• Pleasant and clear narration
• Problems worked in step-by-step detail
• Natural progression in difficulty of problems, with each new characteristic thoroughly explained
• Multiple examples worked of each type
##### Cons
• Presentation works exclusively with discriminant-style radical expressions, without mentioning other forms the learner might encounter
• No mention of checking the result values of x for accuracy
• No printable note slides provided
• Homework/guided practice problems not available