# Week 7 – \$600 Bouncy Balls, Building Robots, and Decimal Division

It’s been a fairly good lucky number week 7.  Had our first auction and started to build robots.  Content has been going well for the most part, with exception to some pretty dull 6th grade math lessons.

### AUCTION

We had our first auction in our classroom economy. Each class has an auctioneer who goes around to businesses to fundraise items for the auction.  Didn’t have a ton of amazing items on this first one but last year I had students who got the entire Hunger Games hardback trilogy donated, iTunes gift cards, \$50 toy robots, and a few dining gift cards.  Ironically, it’s things like a brownie or a Dr. Pepper that end up selling for more than anything. Pretty interested economics and ‘immediate gratification’ at work there.  Had a bouncy ball sell for \$600 today (while a book sold for \$75).  Some students actively abstained from any bidding because they’re saving up to buy their desks so they don’t have to pay rent anymore.

### BUILDING ROBOTS

In robotics, they’re finishing up taking inventory on their robot kits (so I can see if there’s any major parts I have to order) and have begun building.  There are a couple of easy robots to build but students wanted a challenge.  I ended up finding a robotics curriculum that has some building instructions for some more interesting looking bots.  Unfortunately, the building instructions weren’t super clear so kids are running into problems with not really being able to tell how some pieces fit together.  It’s a good lesson in improvisation for those who are more familiar with the LEGO Mindstorm kits already.  Those who are new to building went for the more straight-forward bots.  Excited about the curriculum I found though; plan on tweaking the little-projects and having them do blog reflections for each build.  The students kept insisting we listened to the Interstellar soundtrack while building.

### PRE-ALGEBRA

We finished up working with order of operations this week and I focused on presenting more algebraic looking problems but without any variables yet.  They incorporated quite a bit of roots and exponents to help spiral the previous lessons.  Students were pretty satisfied that they were actually able to simplify somewhat daunting expressions:

We started exploring scientific notation and I tried to go about giving them a more conceptual understanding of what’s happening when you multiply by 10 to some power, instead of just saying ‘now count the place values and that’s your exponent!’  Some of the kids made that discovery on there own which I love, but I didn’t want to just teach the shortcut without exploring the concept a little more deeply.  HERE’s my slide show of the lesson.

I’ve been struggling to figure out how to teach division of decimals (and really just re-teaching long division) in a more discovery-based sort of way…where they see visuals and connect it to the standard algorithm.  We just finished multiplication of decimals and I didn’t want to just say ‘COUNT THE DECIMALS AND THEN ADD THEM BACK’ without talking about what was actually happening when you multiply decimals.  When you ‘get rid’ of the decimals, you’re actually multiplying by a multiple of 10 to turn the decimal into a whole number (multiplying by 100 if you have two numbers after the decimal).  The total amount that you multiplied all your numbers by 10 is the same amount you that divide your answer by 10.  Three numbers after the decimal is multiplying by 1,000, so when we get our answer, we divide by 1,000 (move the decimal back 3 spaces).

It was pretty cool when some students came back with the homework and did some research on their own and shared that you could just count the decimals and bring them back at the end.  One student said ‘well that’s just the same thing as multiplying by 100 and then dividing by 100 at the end.  SUCCESS!

We will start dividing decimals early next week.  I sort of had my own aha moment when I was planning the lesson with recognizing what’s happening when you put ‘.0’ at the end of the number to divide completely.  Hoping to share visual with them and have them connect it to the standard algorithm; hopefully it’ll lead to understanding.  Here’s the slide show I will have them walk through with a partner and share patterns and connections they see as they walk through the slides.

I solved my reading light problem (it was so bright that it defeated the purpose of trying to read with little light so my wife could sleep).  The idea came to me as I had toilet paper lying around to plug up my allergy-stricken nostrils.

##### By Thom H Gibson

I help middle school STEM teachers create meaningful & memorable experiences for their students. Teacher, podcaster, YouTuber. Two-time teacher of the year