The previous two lessons have led up to the content covered in today’s powers of ten lesson. I begin this lesson by displaying the revised version of the I can... statement involving powers of ten. Students echo the statement.
I can explain patterns when multiplying a number by powers of 10. Repeat it with me. Today we are going learn what powers of ten are and the benefit of using them.
I provide students with a copy of the worksheet Secret Worlds: The Universe Within. This worksheet will guide students through the web interactive we are going to use today. The interactive is out of Florida State University page, Molecular Expressions: Science, Optics, and You. I start the interactive at oak tree branch with leaves.
We are going to zoom out 10 times which is like multiplying by 10. Let’s write x 10 on the distance for our first scene.
I fill in the distance only on the first line of the chart. I then hit the increase button again and it brings us to the nearby trees scene. I tell students we zoomed out 10 more times so let’s write 10 x 10 for the distance of the second scene.
Let’s use our knowledge from previous lessons to determine what multiplying by 10 twice is the same as. If we multiply 10 x 10 that is the same as multiplying by what? Explain your thinking?
As a class we go back and fill in the "or" column of the worksheet for the second line so it reads x 100. We continue to go through the interactive, filling in the Distance and Or column.
Up until this point in the the unit, I have worked on laying the ground work for understanding powers of ten. Now it is time to introduce what a power of ten looks like and how to write it.
Did anyone get tired of writing x 10 while viewing the interactive? Would you like an easier way to write it?
I refer back to the worksheet that we just completed and begin at the second line where the distance is 10 x 10. I ask the students to tell me the number of tens I multiplied. I then show them how to write 10 to the power of 2. I do the same for the next line this time focusing on how to say the index notation.
Say it with me. 10 to the power of three. And the first one we did…. 10 to the power of two.
I have students work within their groups to complete the remainder of the worksheet.
To check students' understanding of powers of ten I bring the students back to the large group and ask them a series of quick questions.
Alright, who can tell me what the distance of our solar system is? How about the distance of the southeastern United States? What would we be able to see if we were 10 to the power of 10 meters away from the oak tree?
After asking a few questions I open it up to students creating questions and asking the class.
To further assess students’ knowledge of powers of ten, I provide simple multiplication problems involving powers of ten. I write the problems on the whiteboard and have the students answer the questions on the back of the worksheet we used earlier in the lesson.
9 x 102 =
83 x 102 =
9 x 103 =
83 x 103 =
9 x 104 =
83 x 104 =
I then ask students to look for some potential patterns in the powers of ten multiplication problems. I guide them through a self-discovery of determining that when multiplying by a power of ten, you add zeroes to the number in the amount equal to the exponent of the power of ten.
I ask students to repeat the I can... statement for the day and to explain the statement in their own words by writing their knowledge of the statement on the worksheet. I monitor student responses for accuracy.