Lower School Classroom Chronicle

October has many milestones: Fall Parent Conferences, Indigenous Peoples’ Day, and finally, Halloween. But, I bet you didn’t know that in third grade October is the month of plastic one liter bottles! As part of Number Corner in the Bridges math curriculum, students learn how much liquid it takes to fill a one liter bottle.

Discussions start by asking the question: How do we measure liquids? Do we use inches, a ruler, a scale, pounds? Many third graders have heard these terms and several know what each one is used for, but sometimes they are not as familiar with the term ‘liters,’ or ‘milliliters.’

Each day a student comes to the front of the room and pours 250 milliliters into an empty liter bottle. Everyone records how much liquid we have in the bottle (250ml) and also how much of the bottle is yet to be filled (750ml). We make predictions as to how many liter bottles we will be able to fill before Halloween if we add the same amount each day.

These are rich math opportunities designed to help develop a sense of metric units of liquid as well as to apply skills in reading, understanding, and adding multi digit numbers, fractions and mixed numbers. Cheers go up as we fill the last 250ml. How many liters did we get this month? 

*Editor's note: Nearly all (195) countries use the metric system to base measurements. Only three countries do not use the metric system: United States, Myanmar, and Liberia.