Provide your students with a box of candy hearts or for a more economical way buy them by the large bag and dump them into mini Dixie cups. Each student should also, have their estimation sheet. I printed mine on card stock and laminated them, so they can be wiped off after each use. Each student should also, receive a Dry Erase marker to write their estimation, as well as their final count.
Once each student has all of the supplies talk to them about estimating, have them make their guess and then place the candy hearts inside the heart. When they are finished count them up and write the actual number that fit inside the heart.