Dividing Decimals and Spinners

My students have been exploring decimals for the past week and a half. The class identified place values, rounded and placed digits up to the thousandths on number lines. While looking for ideas I came came across Erick’s response to my Tweet about decimal division. After reading Erick’s post, I delved a bit deeper into how to connect the activity with my upcoming standards related to decimal addition/subtraction and long division. I did not have the connected blocks needed for the activity so I asked the kindergarten teachers. Fortunately they had a few boxes that I could borrow. Some of the already connected blocks were stuck together. Trying to pull them apart the first time took Hulk-like strength (as one of my students mentioned). I then put together a few questions for students to follow as they progressed through the task. The questions were placed in Canvas and formatted as a quiz with image uploads.

I randomly place students in groups of 2-3 . Each group was given a bag with 15-30 blocks.

The groups were given around 10-15 minutes to create a prototype. Groups used trial-and-error to figure out what helped the top spin more effectively.

I found out quickly that not all snap-cubes are created equal. The one on the left in the picture spun longer (I think it was 5x) than the right. Since this was not considered a competition I do not think it mattered to much, but this is something to consider moving forward. Students then went into the hall to find a flat surface and timed the spins and recorded it on their sheet.

Groups then added the trials together to find a total.

Students were then asked to find the average time for the trials using the long division algorithm. Based on the student responses, this seemed to be the the most challenging part of the task. Most groups estimated the quotient first and used that as a baseline. Students then used long division (they are used to using partial-quotients) to find the quotient and remainder in decimal form. They were required to round to the nearest hundredth during the process.

Some groups were required to round a repeating decimal, which was a new skill for them. Groups then shared their spinner with the class and the strategy that was used during the creation process. I was impressed with the different models and the teamwork that was demonstrated by most groups. This is a task I am planning on trying out again in the future.

Major kudos to Erick, Jen and Mike for the ideas!

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