Khan Academy and Computations in Scientific Notation

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SWBAT to multiply and divide with numbers in scientific notation.

Big Idea

Students need as many opportunities to practice and reflect as we can give them.

Assessment Overview

10 minutes

This assessment can be done at home or in class. Either way, I ask students to prepare for the assignment by watching the video I created to help students. 



This activity can be incredibly helpful if students slow down and take the time needed to think about what they are doing and why it makes sense. 

Khan Academy is constantly changing its layout and its scoring system, but for this activity I would ask students to log in (optional) and work until their achieve mastery. This is a topic you need to discuss with students. "Mastery" in Khan Academy might mean something like getting 20 correct, but I want students to complete about 10 questions and only continue if they think they need more practice. I encourage them to stop and reflect. They need to self-assess, "do I need more practice?" 

The Assessment

40 minutes

There are currently 5 scientific notation exercise sets on Khan Academy.

I like some of the questions in the module, because they can be solved mentally with some simple manipulation. However, there are quite a few that are extremely difficult to solve mentally (even with significant manipulation). Because of this (and this is important for the students), I tell them to try and solve each problem by without using a calculator. However there are a few division steps that might require long division or a calculator.

So I give students a calculator and acknowledge that this module lends itself to tedious calculations. However, even when they use the calculator, they should be able to manipulate the terms to make the problem more manageable.

My general advice here is to make sure you site down and go through the exercises before you assign them to your students. Your expectations for a module might not match what they actually ask the students (we will see some examples of this in other units).

The structure of the site is overwhelming to many students. To simplify the process, I have them log in to Khan Academy and then open a second tab and go straight to this link:

Computing in Scientific Notation

They could also go to the exercise dashboard and type in "Computing in Scientific Notation."

Exercise Dashboard 

Last year I set this up in a series of assignments through my website: 

Shaun Teaches

This exercise is new and was not used last year, but I will use it in future assessment lessons.

The key is to ask students a follow up question. The guidelines are as follows:

1. Finish the Multiplying and Dividing Scientific Notation Exercise Until you reach "mastery"

2. As you work, write the questions and answers in your notebook

3. When you are finished, annotate your notes and explain some general observations you made as you worked. 

4. Create solve and explain a challenge problem that would fit in this exercise group. Note: It should look complicated but break down nicely. In other words, a student that can manipulate the problem should be able to solve it mentally. 

I usually ask for the part 4 via email. However, this one might be very difficult to write in an email. So I ask for part 4 on paper or using an equation editor via Microsoft Word or something free like Daum Equation Editor. Since all students have set me up as a coach I can easily monitor their progress after class. I circulate during class and help students by asking them reflective questions, like "when you move the decimal, what are you doing to the number?"

I collect the notes from at least one student who has mastered the topic and one who is struggling.

Assessment Review

10 minutes

I finish this assessment by reviewing questions with the class. I log into Khan Academy and project for the whole class to see. I popcorn around the room and ask students to solve and explain. For each question I get at least 2 algorithms, since students love to hear other strategies. I have noticed that many students use one strategy throughout all the problems and are usually so tired of it by the end that they crave a more efficient strategy. I wait until the end to share all strategies because I believe that process of struggling helps them process the importance of a more efficient strategy. If we just shared at the start, I think many students would blindly plug in the more efficient strategy without understanding why or how it is efficient.