Wednesday 17 February 2016

Log Clothesline

There has been quite the buzz around clothesline activities of late. There is even a website! I first heard about it from Andrew Stadel when he wrote this post. More recently, Jon Orr made a cool one to practice finding slope. Here is a link to his blog post. I thought that it would be great to use a clothesline to practice evaluating logs, but was having trouble finding the time to actually create it. Then we got a snow day (school buses are cancelled, but teachers still have to report to work... all of the students at my school take the bus so we have a day with no students) but I had other things to do (like meetings) and we were allowed to go home early (we got 51.2 cm of snow by the end of the day!). And then, shockingly, they cancelled the buses again today! So here is the log clothesline for you. I plan on actually doing it with my two MCV4U classes on Friday and and will snap some pictures then. I did take a "fake" one of a colleague placing a card on the clothesline.

Here is the Word file, and the PDF version is here. And I'll even give you the answers. I numbered the pages so those correspond to the question numbers, which I have sorted in the Excel file so that I can quickly check for correctness. I printed two pages per sheet and cut them down the middle.

I will give out one card to each student and they will have to evaluate their expression and check at least one from someone else in their group. Once the whole group is confident in their answers, they will go to the clothesline to place their expression in the correct location. I will give them a 0 marker on the number (clothes)line. The trick is that I will tell them that they can't write on the cards so in order to figure out where their card goes, they will have to work out a number of other expressions. Those students who put their cards up first will be responsible for ensuring that all the cards that follow are in the right place.

I will try to write a "how it went" blog post after I run the activity.


After hitting publish this morning I started to think more about this activity and started questioning whether it met the spirit of clothesline activities. I worried that as it doesn't really work students' number sense, it might not be an activity worthy of sharing. I sought advice and, though we agreed this would be better suited to an intro to logs activity (more on that in a minute), this practice, with built-in error analysis and collaboration, was worth sharing. 

Back to the intro to logs idea. This is what I envision: students get cards with powers of 2s from 1/64 to 32768 (or something like that, depending on the number of students in the class) and they have to attempt to place them on a clothesline that will have markers of 0 and 1 on it (not as shown below). It would look something like this:

Hopefully it will become clear that there are too many cards between 0 and 1 and that the larger numbers simply cannot fit on the clothesline. So what to do? I'm not sure how to introduce the idea of taking log base 2 of each of the numbers, but that will be the goal. The result will be a clothesline with a logarithmic scale which will allow all the numbers to be seen. I won't actually be able to do this until next fall, so please let me know if you try it out!


  1. This looks great Mary -- I plan to try it out when we do logs in Precalc likely about late March/early April. How many s's are in your classes? I only have 12 students and wonder if each s should get 2 cards or perhaps teams of 2 get 3 cards
    PS do you store all your lessons in something like Live Binders? I find so many good resources or create my own but need to find a way to know where they are

    1. Thanks fore reading, Robin. Our classes have a cap of 30 (at this level), but it varies. I have a smaller class in the afternoon and may have the groups do a few extra cards.

      I keep my lessons in folders (not a livebinder) by course. When I find things from others, I send myself the link and tag it with the appropriate course code and content so I can search for it later.

  2. Mary, I think your original activity would be wonderful to use in the Advanced Functions course. It would be a different way to have the students practice evaluating logs without their calculators.