The Montessori Long Black Strip: A Powerful Tool for Teaching Children the History of Earth

    The Long Black Strip is a Montessori material that is used to teach children about the age of the Earth and the relative shortness of human history. It is a long, black strip of fabric that is unrolled to represent the 4.6 billion years since Earth’s formation. A small, red strip at the end represents the approximately 200,000 years that humans have been on Earth. The purpose of this lesson is to help children to understand their place in the universe and to appreciate the vastness of time.

    The Long Black Strip is typically presented to Lower Elementary children though sometimes it can be given to Upper Elementary as well. The teacher will unroll the black strip and tell the children a story about the formation of the Earth. The story covers the high points from the Second Great Lesson with an emphasis on the precambrian time period. Once the strip has been unrolled, the teacher will point out the tiny red strip at the end and explain that it represents the time that humans have been on Earth.

    The short red strip is a reminder that humans are a very recent addition to the Earth and that we are part of a much larger story.

    This lesson is presented at the beginning of the year, shortly after The Second Great Lesson with the Timeline of Life. Because the strip is so long, you should really try to present the lesson outside if you have the space. I have presented it indoors and we end up winding around the classroom, into the hallways and into other rooms!

    The Rhyme and Reason Long Black Strip

    The original long black strip made by Maria Montessori was 100 yards of plain black fabric, I’ve shortened mine too 100 feet (which is still absolutely massive) and printed it on vinyl. Vinyl is nice because it holds up well outdoors and is easy to keep clean. The vinyl I print on is low-odor, vibrant, and very strong.

    Each quarter inch represents 1 million years.

    This material is a semi-DIY project, the image is printed on a vinyl banner and you will need to cut the pieces apart and glue the strips together. Including drying time, this is a weekend project.

    Materials needed:

    Step 1: Cut the strips apart

    This is the most time consuming step, after this, the project progresses quickly. It took me a couple hours to cut everything out.

    I prefer to cut with a rotary cutter, cutting mat, and quilting ruler because I have these tools on hand. I think it goes a lot faster and the results are nice. If you don’t have those things then a pair of scissors will work just fine, find a comfortable pair though, because you’ll be cutting a little more than 100 linear feet!


    • I found that cutting all of the grommets off first was helpful. They aren’t needed and they just get in the way.
    • Cutting on a table was much easier than cutting on the floor.
    • Roll the strips up gently and set them somewhere safe while you cut out the rest.
    • Get a good podcast. Might I suggest Sold A Story or Philosophy of Education by Montessorium?

    Step 2: Glue the strips together

    Set up your workspace first; I worked over a sheet of aluminum foil which made clean up easy. Put on your apron, grab some gloves and your tools and let’s go!

    The painters tape helps you achieve a crisp line and it holds the pieces together while they dry. I ask you to apply glue over the top of the seam because it makes a secure joint that won’t peel up as easily.

    I have a short tutorial video and written instructions to help you out with this step.

    • Find the piece labelled A and the piece labelled B.
    • On piece A, at the end labelled “Glue A” wrap a piece of painters tape all the way around the end, leaving about an eight of an inch of the orange color exposed.
    • On piece B, go to the non-labelled end. Cut off any visible white, you want the end to be entirely black and orange.
    • On piece B, place a piece of painters tape on top, about an eight of an inch away from the end. Do not wrap it around just yet.
    • Apply glue to piece A where it says “glue.” This should be a good amount, but don’t go crazy. Go right up to the tape.
    • Place piece B onto piece A. Align the orange line as well as you can.
    • Now, wrap the tape from piece B all the way around both pieces. This will hold the two pieces together securely while they dry.
    • Apply a small amount of glue on top of the join. This will help prevent the seam from peeling apart.
    DIY Montessori long black strip

    Repeat the process for the remaining strips, going in alphabetical order. Once you get the knack, this goes really quick.

    Let dry overnight. (This step might actually be the hardest!)

    Step Three: Final Assembly

    In the morning, remove the painters tape with care. You should have crisp, professional looking paint edges.

    Find the end where humans are and use a piece of scotch tape to attach the strip to the dowel.

    Slowly and carefully roll up the strip, you’re done!

    Montessori long black strip rolled up

    Use with the Timeline of Life

    The Rhyme and Reason Timeline of Life has a neat scale feature that you can take advantage of! Unroll the Long Black Strip and place the dowel end where humans are. Then take the other end and (gently) scrunch up all the rest of the strip, lining up the color divisions to the best of your ability.

    Technical Note: In the Phanerozoic Eon, the Long Black Strip scale is 2:1 with the Timeline of Life, so every quarter inch on the Strip is 1 million years, for the Timeline, every eighth of an inch is a million years. I decided not to make them 1:1 because I believed it was more important to keep the traditional 100 feet length of the Long Black Strip.

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