Khan Academy Patterns in Zeros
Lesson 12 of 22
Objective: SWBAT to predict how division and multiplication by ten will change the value of a number
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 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?"
There are currently 5 scientific notation exercise sets on Khan Academy. This one is listed outside of the scientific notation section (still under exponents), but clearly is perfect for scientific notation review. So in a way this is 6th scientific notation exercise that I was able to find.
Unlike many of the other modules, I like every question in this module. I think some could be improved (since every question is about positive numbers, it seems to incorrectly imply that division by 10 always reduces value and that multiplication by 10 always increases value.)
My general advice here is to make sure you sit down and go through about 15 of these questions so that you can circulate with pointed comments. You want to ask detailed questions that help students reflect on thy "why" behind their work.
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:
They could also go to the exercise dashboard and type in "Patterns in Zeros."
Last year I set this up in a series of assignments through my website:
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 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.
5. Multiplying by 10 always moves the decimal right. Dividing by 10 always moves the decimal left. Does multiplying by 10 always make a number value increase? Does dividing by 10 always make a number value decrease? Explain with helpful examples.
I usually ask for the part 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.
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.