It’s hard to believe that 2018 is here, and we’re quickly approaching the 100th day of school. When I first started working with elementary school teachers, the concept of a 100 days celebration was foreign to me—it wasn’t something that we did in high school. Over time, I’ve come to appreciate this tradition and the mathematical opportunities it brings.

In honor of 100 days of learning this school year, here are a few ideas for K-8 including reproducibles for your 100th day activities. Try them out and let us know what you think!


Have students count to 100 by ones, twos, fives or tens. Use Unifix Cubes or counters to help students who are still working on mastering this concept by having them make sets of two, five, or ten cubes until they reach 100.

Measurement and Estimation

Ask students how far they think 100 of an object will reach. The answer doesn’t have to be numeric—it can be two pieces of tape on the floor or two students or other markers. For the objects, use paper clips, Unifix Cubes, color tiles, or any other counter or classroom object. Halfway through the activity, ask students if they want to revise their estimate (or guess), and discuss why or why not as a class.

Data and Graphing

Give students an assortment of 100 counters, Unifix Cubes, shapes or other objects and have them sort by color, size, shape or another characteristic. Count the number in each category, and create a graph using the data. If using Unifix Cubes, they can become the bars of a bar graph (consider using Jumbo Unifix Cubes to make the graph even easier to see)!

The Locker Problem – Perfect Squares

Older students may be challenged by the locker problem, a classic problem-solving activity that can be a good discussion starter for square numbers. If you’re not familiar with the problem, it goes like this: There are 100 lockers in a hallway, and all are closed. 100 students go down the hallway, one at a time. The first student opens all the lockers. The second student changes (closes or opens) every other locker. The third student changes every third locker, and so on. After the 100th student has gone, the lockers that are perfect squares are open. You can model this with a smaller number of lockers and have students expand it to 100 to reinforce the concept.

We’ve also included two activity sheets that you can use to celebrate the 100th day of school.

Here are some links we found to additional 100th day activities that you might find useful. Note that these links will direct you away from the Didax website.

MathWire shares some fun math-focused activities for the 100th day, including some great hundred board activities and literature connections.

Education World compiled a list of 100 ideas for celebrating the 100th day. This list covers several content areas and includes some ideas I haven’t seen before.

The Math Forum has archived some 100th day activity links and ideas.