Math = Love: Nine Dots Puzzle

Wednesday, August 23, 2017

Nine Dots Puzzle

I love brainteasers. I also love finding a way to incorporate them into class. Since the first week of school is rampant with schedule changes (especially this year since we don't have a guidance counselor), I aim to engage my students in math-y activities that get their minds working but don't necessarily tie into the curriculum.

I've decided to do daily warm-ups this year that students will keep in their interactive notebooks. School started on Monday, and we won't be setting up our notebooks until tomorrow (Thursday). This means that my students needed a place to keep their warm-ups until notebooks were set up.

Introducing the Warm-Up Divider!

At first, I wasn't sure what to put on this divider. Then, I realized I could put warm-ups ON the warm-up divider. Can't believe it took me so long to think of that!

I did this for both my Algebra 1 classes and my Chemistry class. The divider pictured above is for Chemistry.

On Tuesday, I assigned them one of my favorite brain teasers: the nine dots puzzle. Without lifting your pencil (or dry erase marker), draw four straight lines that pass through all nine of the points. Since this one is a bit tricky, I decided to make them a dry erase template that would give them lots and lots of chances to try and solve the puzzle. I figured if they had to draw and erase too many times that they would just give up.

Here's what I came up with:

 When I gave my chemistry students the option to use the dry erase template yesterday, almost every kid chose to use it! I think only one student went without, but he came in late anyway. I'm assuming he just ended up copying off of the person sitting next to him. :(

Each table's folder had templates inside. Kids just had to slide the template into one of our dry erase pockets (affiliate link). If you don't have a set, they are one of the best investments I have ever made for my classroom. You can find them on Amazon super-cheap if you search for "shop ticket holders." 

Action Shots:

The kids really struggled with this one, so the dry erase template really paid off!

Download the file for this activity here.


  1. Sarah, It is so cool that you are teaching 9th graders for most of your day this year. I am also teaching 9th graders for my entire day this year :-) I am also determined to get started blogging this year about my class instead of just enjoying the benefits of improving my teaching by everyone else's posts. Now that I finally finished my dissertation, and I am sort of settled in my new school, I will really want to make the time.
    Best wishes for a wonderful year!
    Love the idea of the warm-up section in the notebook. I do a spiral homework for the week and students do their warm-ups on the back of their homework paper. That way they are ready to go editing homework as soon as we go over the warm-up. I give bonus points on the homework for the warm-ups.

  2. These are fantastic! I love these brain teasers. They're tricky, but doable. I think the 9 dots puzzle is a great puzzle to do with geometry students when learning about collinear points. Is your husband also doing brain teasers this week?

    1. He did about a day or two of brainteasers and then jumped straight into curriculum.