Counting objects: 1, 2, 3, etc., is amazing. You can count sheep (a) and record each one that has been counted by making a tally mark (b), then count the tally marks and record each one that has been counted by sliding a bead along a wire of an abacus (c). The number counted remains the same no matter how many times this is done or in what order each one is counted. Whenever an object is counted it is erased (/) from consideration and a new object recording the count is brought into consideration.
