Engaging students: Laws of Exponents

In my capstone class for future secondary math teachers, I ask my students to come up with ideas for engaging their students with different topics in the secondary mathematics curriculum. In other words, the point of the assignment was not to devise a full-blown lesson plan on this topic. Instead, I asked my students to think about three different ways of getting their students interested in the topic in the first place.

I plan to share some of the best of these ideas on this blog (after asking my students’ permission, of course).

This student submission comes from my former student Lyndi Mays. Her topic, from Pre-Algebra: the Laws of Exponents (with integer exponents) While thinking about different activities that I could do with Laws of Exponents I decided to try making a bingo card. I like this idea because it’s a way for students practice on different problems while playing a game. The way I have it set up to use in a classroom, I have questions that I would ask. One example is . I would put this up on the board and the student has to solve it and see if they have the answer on their card. I would tell the students what the answers were until after we were done with the activity so that they’re not just waiting to hear the answer instead of doing the work. If a student got a “bingo” then I would check their answers and if they got them all right then I would have an incentive like 5 extra points on a homework assignment of their choice or something along those lines.

So, if I wrote on the board the equations $x^4(x)$, $x^0 y^5$, $(2x^2-3y^5)^0$, and $x^5 y^{-2}$ . If a student received this card, then on these questions they would get a “bingo” on the descending diagonal from left to right. You’ll also notice that I included some wrong answers in a few of the spots. Hopefully the students would notice they were not all the way simplified and would know they couldn’t use those.

Students can use Laws of Exponents to help them understand Laws of Logarithms. They will use the Laws of Exponents throughout Calculus courses when taking the derivatives or integrals of different problems. It’s important for students to understand these laws so that they can simplify problems and use them to their advantage. One example is when the student is asked to solve $\int x^{-4} \, dx$. If the student has a good understanding of the Laws of Exponents, then their first reaction will be to change it to $\int dx/x^4 = -1/3 x^3 + C$. Having this understanding is necessary for this problem and helps when students already know the Laws of Exponents so that they’re not having to learn extra material basically.

Archimedes is the one that discovered the Laws of Exponents. He did this by breaking everything down as much as possible. To show an example,

$3^4 \times 3^2$ = (3×3×3×3) (3×3)  We can do this just by know the definition of exponents

= 3×3×3×3×3×3     Once we remove the parentheses we see we’re just multiplying 3 together 6 times.

= $3^6$                         This is just the definition of exponents again

Teaching the students the Laws of Exponents this way can show them how a mathematician discovers all these rules that we follow and gives them a better understanding of the laws. Opening up this interest might help the students become more interested in math. Another example that I would show students would be $y^5/y^3$. From here I would show the students that we could break it down to $(y \times y \times y \times y \times y)/(y \times y \times y)$. Hopefully, then the students would see that you could divide and get rid of the denominator, $y×y=y^2$, and this is why it is ok to subtract when a term with an exponent is being divided by something with the same base. This is also a really good way to show students why they can NOT use these laws when they’re working with terms with different bases.

References:

Exponentiation. (2017, September 1). In Wikipedia, The Free Encyclopedia. Retrieved

23:05, September 1, 2017, from https://en.wikipedia.org/w/index.php?title=Exponentiation&oldid=798388543

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