These are the estimation jars I had in my classroom math center recently. Our school library (in a PreK-8th grade school where I once taught) there was an estimation jar with a lot of little items in it, such as jelly beans. It was not easy even for me to estimate a big jar full of jelly beans or candy corn, so I don’t know how young children could even begin to estimate the amount.
Here’s how I made estimation jars for Pre-K that will make more sense to the children. I made four jars:
- The first jar had one marker in it with a numeral 1 taped to the front.
- The second jar had three markers with a numeral 3 taped to the front.
- The third jar had six markers with a numeral 6 taped to the front.
- The last jar had ten markers with a question mark taped to the front.
This way, the children can see what one marker looks like in a jar, what 3 looks like, and what 6 looks like. They can then use that visual knowledge to estimate how many are in the last jar.
I placed a basket of recording sheets beside the jars for the children to write their guesses. (Download link to the recording sheets below.) After everyone has had an opportunity to guess, we will count the markers in the last jar during our large group time.
I’m planning to put different items in the jars each month, so the children will have a lot of practice during the year. I know someone will ask: the jars I used came from Walmart (kitchen area) and they are clear plastic. The lids fit on with a rubber seal so they don’t come off too easily.
Estimation Jars for the Year
|October||Plastic Pumpkins or Spider Rings|
|November||Pinecones (same approximate size)|
|December||Candy Canes or Ball Ornaments|
|January||White Styrofoam Balls (“Snowballs”)|
|February||Candy Hearts or Plastic Hearts|
|March||Small Plastic Animals or Bugs (same approximate size)|
|May||Sand Volume & Water Volume|
|June||Seashells (same approximate size)|
|July||Small Bouncy Balls (“Beach Balls”) or Small Fruit (Kiwi or Strawberries)|
More to estimate:
- Tree nuts (pecans or other)
- Gift bows (Christmas or Birthday theme)
- Bear counter manipulatives
- Unifix cubes
- Cube dice
(Clipart by Rainbow Sprinkle Studio.)