Measure liquids and do the math. When we have a unit to measure, the math is the same as it ever was. This activity proves regrouping. Fill up the 10 !
Preparation
The vases take some time to label. With heavy tape they can last more than a year. To prepare the tape, find the total capacity of the vase or glass you’ve chosen, (the math is much easier if you use milliliters ) and divide that by ten. Put the tape on the side, pour in one tenth at a time and mark it. Test your tape several times to see that you’ve placed the tape correctly and usefully.
Have students show a typical regrouping problem such as 8 + 5. Fill one vase with 8 units and the other with five.
We fill the first glass with 8 and the second with 5. If I pour the 5 into the 8 glass, will it be ok? Is there enough room in the first glass to hold 8 + 5 ? Lets try it with the counters and see what might happen to the water.
If we take two from the five , we can fill up the ten. The student pours from the five bottle to fill up the 8 bottle, and stops before overflowing. Look at the second bottle. It still has three left. The first bottle counts as ten and the second still has three. What is 10 + 3 ?
When we measure liquids we can use the numbers just like we add and subtract any other numbers. That is how we can count how much milk, water or oil to use in a recipe. That’s how grownups know how much gas they need in their car. Let the students talk about it and use what they say to show them what to write about what we learned in their journals.
