So you could have a bunch of pencils for the children to count or to sort.
You could get pencils that are different colors and have the children sort them into cans with construction paper covering it that is the same color as the pencil.
You could have 6 cans with the numbers 1 to 6. Have the children place one pencil in the 1 can and 2 in the two and so on.
You could sharpen 5 pencils to different lengths, then have the children line the pencils up from shortest to longest.
Find colored paper clips and have the children sort the paper clips according to color. Place the numbers 1 to 6 in the bottom of each of the cups in a muffin tin. Have the children place one clip in the one, two in the two and so on.
Create a pattern with the colored paper clips. Red, blue, red, blue have the child continue the pattern. Ask the children to create their own pattern.
Grab a few paper clips and set them out on a paper plate. On another plate, have the children copy the design.
Estimating Jar You will need 4 clear jar that are the same size. Fill one jar about 1/4 of the way with paper clips. Count the clips as you fill the jar and end on a round number, like 10 or 50. Write the number of paper clips on a post it, place the post it on the jar. Fill the second jar about 1/2 way with paper clips, again counting and recording and posting on the jar. The third jar should be filled about 3/4 of the way with clips and again record the number and post it on the jar. The last jar you can fill however you like, place a post it on the jar with a question mark. Allow the children to observe the four jars together and guess how many clips are in the fourth jar. Record the children's guesses. After everyone has guessed, count the clips together. Show the children how the number of clips in the first three jars are related to the fourth jar.
You can do any of the activities above with erasers as well.