Khan Academy and Scientific Notation Intuition

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SWBAT to describe the connection between the movement of a decimal and value of the power of ten in scientific notation

Big Idea

When we move a decimal, we can balance our value by changing the exponent we use

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. 

Scientific Notation Video


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 have had many students complain about Khan Academy. They get frustrated, because if they make a single mistake they need to basically start from the beginning. They find this discouraging. They kept working and working even when they understood the topic. They spent hours trying to get "mastery" and would give up if they hit the wrong button or number. Instead, they need to stop and reflect. They need to think, "do I need more practice?" 

The Assessment

40 minutes

There are currently 5 scientific notation exercise sets on Khan Academy. I recommend them all, but this one is my favorite. It gives students easy access to the math and is fun to talk about. If the assessment is done right, it can lead to a real breakthrough for students. 

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

Scientific Notation Intuition

They could also go to the exercise dashboard and type in "scientific notation intuition."

Exercise Dashboard

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

Khan Academy Notes

It looked like this: Khan Assignment


The key to my approach is to ask students a follow up question.

The guidelines that I give students are as follows:

1. Finish the Scientific Notation Intuition Exercise Until you read "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. 

5. Answer this question and use examples to support your reasoning: Why is it that when we drag a decimal point to the right, the value of the exponent decreases? Why is it that when we drag our decimal point left, the value of our exponent increases? Give an example to help explain.

I usually ask for the parts 4 and 5 via email. 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 1 student who has mastered the topic and 1 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.