What’s Wrong with “Repeated Addition”? « Let's Play Math! [Photo by Alejandra Mavroski.] Myrtle called it The article that launched a thousand posts…, and counting comments on this and several other blogs, that may not be too much of an exaggeration. Yet the discussion feels incomplete — I have not been able to put into words all that I want to say. Thus, at the risk of once again revealing my mathematical ignorance, I am going to try another response to Keith Devlin’s multiplication articles. Let me state up front that I speak as a teacher, not as a mathematician. I will start with a few things we can all agree on… We All Agree on Some Things Elementary students will use addition to solve beginning multiplication problems. So What’s the Problem? So what is wrong with the definition, “Multiplication is repeated addition”? To define multiplication as repeated addition is to make multiplication a sub-species of addition. The operation of addition has its identity element. And they are not the same. Every number has its own additive inverse. But…
Removing Super Glue | Super Glue Corporation Super Glue is renowned the world over for the strength of its bonds, its versatility of use, and easy application. Whether a hole needs a seal or a crack needs repairing, Super Glue is the first thing that craftspersons, hobbyists, and contractors use for all their construction or repair needs. Because Super Glue is so strong and bonds so fast, some people may find that they have accidentally glued two fingers together, or found that that small piece of balsa wood or plastic from a model they were building has completely bonded to their skin! Acetone is often found in household nail polish remover, and a small amount on the end of a Q-tip or cotton swab applied directly to the glue should dissolve the bond without damaging the skin. Be careful - straight acetone will discolor a number of fabrics and can mar the finish of laminated counter tops (mainly the darker colored ones). Immerse bonded areas in warm, soapy water.
ESL Teacher Handouts, Grammar Worksheets and Printables Free English grammar and vocabulary worksheets and printable handouts, for English language and English as a Second Language (ESL) teachers and instructors to use in the classroom or other teaching environment. Get our ESL handouts newsfeed: Beginner English Handouts Adjectives and Adverbs Articles Comparatives & Superlatives Conjunctions Determiners A, An, Some or One (8) General Modals Must & Can (10) Nouns Parts of Speech Prepositions Present Simple Pronouns Pronunciation Pronunciation of 'th' (10) Questions Relative Pronouns Relative pronouns- Which & Where (10) Since and For Some & Any Spelling and Punctuation Syllables How many syllables? Verbs and Tenses Vocabulary Intermediate English Handouts Conditionals Direct & Indirect Speech Indirect speech (15) Future Forms Gap Filling Gerunds and Infinitives Idioms Singular & Plural- Noun + Noun (10) Passive Past Simple Phrasal Verbs Prefixes & Suffixes Suffixes: -dom, -hood, & -ship (10) Present Perfect Question Tags Indirect Questions (10) Which syllable is stressed? Collocation
Transform your Presentations with Visme Brain research is crystal clear. We need to find different ways to represent material to students. I am always looking for new ways to present information and came across Visme. It comes in both a free and paid version. What is Visme? If you have never heard of Visme, it is a compelling and engaging presentation tool that may come in handy in your classroom. How Do I Use Visme? Step 1: Create Your Visme Once you create a free account, you can choose which type of presentation that you would like to create (i.e. Step 2: Create and Add Content Once you have chosen what you want to create, you are now ready to begin adding content. and multimedia. Step 3: Publish When you are ready to share your Visme with the world, you can choose to publish. Why Use Visme? Once you create a Visme presentation, it can be presented anywhere and on any device! Visme provides you with powerful tools to give a presentation or communicate your ideas, statistical information, reports, or web content.
100+ Google Tricks That Will Save You Time in School – Eternal Code [via onlinecolleges.net] With classes, homework, and projects–not to mention your social life–time is truly at a premium for you, so why not latch onto the wide world that Google has to offer? From super-effective search tricks to Google hacks specifically for education to tricks and tips for using Gmail, Google Docs, and Google Calendar, these tricks will surely save you some precious time. Search Tricks These search tricks can save you time when researching online for your next project or just to find out what time it is across the world, so start using these right away. Convert units. Google Specifically for Education From Google Scholar that returns only results from scholarly literature to learning more about computer science, these Google items will help you at school. Google Scholar. Google Docs Google Docs is a great replacement for Word, Excel, and PowerPoint, so learn how to use this product even more efficiently. Use premade templates. Gmail Use the Tasks as a to-do list.
Speed Arithmetic Return to my Mathematics pagesGo to my home page © Copyright 1998, Jim Loy Addition of two numbers: Let's add these two numbers in our heads (i.e., without paper). Memory is why speed arithmetic experts (I call them "arithmetickers") usually add numbers like these from left to right. Let's try again: 2+9=11, 1+3=4, 6+2=8, 6+7=3 and that previous 8 should have been a 9 (because of the carry). Addition of columns: How about this addition problem? In the right column, a speed arithmetic person might group the 9 and the 1 (10), the two 5's (10), and then the 7+2+4 (13) to get 33. Instead, what I do is add 29+37=66, then 66+15=81, then 81+21=102, 102+32=134, 134+85=219, and 219+44=263. Multiplication: 24 x48 ---- Speed arithmetic people multiply from left to right, too. 2x4 = 8 2x8 = 16 ---- 96 4x4 = 16 ---- 112 4x8 = 32 ---- 1152 See how that is done? Why? Why should a person learn to do this? Addendum (tricks): Older speed arithmetic books dwelt almost exclusively on tricks.
Updates: The Get Off Your Ass Manifesto: How to Motivate Yourself to Actually Achieve Your Goals By Thorin Klosowski Starting something new is hard. It can even be a little terrifying. Maybe you don’t know where to start, or maybe you’re scared of failure. But the only way you’ll ever get anything done is if you just get up and do it. We all have unfinished projects, and a lack of motivation is one of the biggest reasons we don’t accomplish them. (1) I don’t know how, (2) I can’t afford to pay someone else to do it, (3) I have to do it, (4) hey, that wasn’t so hard! Getting off your ass and getting things done is not easy—nor will it ever be—but it doesn’t have to be hard. Find your goal: You don’t even have to do anything—just sit and think about what you want to do.Research: The more research you do, the easier the task in front of you is going to be. The whole process of getting off your ass and motivating yourself really is that easy. Find Your One Goal and Write Your Manifesto This is where the manifesto comes into play. Research What You’ll Need Set Deadlines and Stick To Them
ELLA » Teachers’ Corner Here you can download some of the materials you can find in this site: those that we have made ourselves. The zip lessons are compressed into a zip file that you will have to extract to a shared folder in your server. To start the lesson open the file: index.htm and follow the links. All the video files are flv, if you can't play them in your computer you will need to download and install an flv player like VLC player. Check the FAQ for more information on this Units marked* are not available yet but will soon be released Elementary A Mobile World zip pdf video and audio A Healthy Flight zip pdf video How to Tie a Tie zip pdf audio and video How to Add Veggies to your Diet zip pdf video Going to the Doctor's zip pdf video It's so British zip pdf video and audio A Day in Town zip pdf audio Intermediate The Thumb Generation zip pdf video The Trial zip pdf video Why Should I Tip a Server? Advanced Cell Phones, could we Live without them?