I had used these same p traps before, but I used them for whisper phones. You can find the perfect size for kids and adults. The beauty of these p traps is that you do not have to do any prep for them to work!
The "Addition Machine" p drain has a very easy to use drain at the bottom. My three year old is able to open it. I added an addition sign to the middle of the machine, so it gives a visual that you are adding both sides of the adding machine.
To make this work, you need 3 small containers and something to prop the "Addition Machine" up against. I used a small stool from IKEA. It is exactly the right size to fit my "Addition Machine".
To prep the "Addition Machine", you need a dry erase marker and some small manipulatives. I have used pom poms, marbles, and any small little things that I find around the house.
First, you write two numbers, with your dry erase marker, on each of the top two containers. On the bottom container, you will write an equal sign.
Students will count out the correct number of manipulative and put them in each of the top two containers. We always counted out loud and examined the two sets of manipulatives before moving on to the next step.
After putting the manipulatives in the containers, I had a student pour each container into the "Addition Machine". We stated the addition sentence, as we went through the process. The addition sentence, in this case"2+4", is the magic password that gets our "Addition Machine" to work!
After all of the manipulative are poured into the "Addition Machine", we say the magic sentence "2+4" again and this time open up the drain. All the kids seem to hold their breath, as the manipulatives pour from the "Addition Machine".
Before we recite the entire addition sentence, "2+4=6", we pass around the lower container to see the magic that has happened. Each set of manipulatives from the containers has mixed together to form the whole!!! It never ceases to amaze! This activity is great for a concrete way to examine Part-Part-Whole.
After we all examine the manipulatives and count how many there are in all, a student will write the sum on the lower container. Then, we are able to recite the whole addition sentence: 2+4-6.
I've had kids want to do this activity over and over, not even realizing that they are practicing addition. Such fun and it really helps those kids that need the hands on, concrete learning.
Hope this can help you, as much as it has helped me! Don't forget the p drains, without a cleanout spout can be used for ready made "whisper phones". Buy and use. My kind of materials :)
I also linked up with The Preschool and Kindergarten Community. Be sure to check there for tons of great ideas!