Hidden Objects

Count, add, and subtract to figure out how many counters are hiding from a small set.

2+
Low teacher engagement

Materials


  • Five identical counters (for example, five red square blocks)
  • Number line or five-frame
  • One object large enough to cover all the counters. It can be made of anything, including a piece of paper or fabric, a cup, or a hat.

Setup — less than 5 minutes


  • Gather the materials.
  • Set out five counters, a number line or five-frame, and a cover object. If the students have used a number line or five-frame previously, choose the one with which they are familiar. Students may need support initially to use these tools.

Instructions

1. A pair of students takes turns being the Guesser and the Hider.
2. The Guesser places the five counters in each spot on a number line or five-frame.
3. The Guesser closes their eyes, turns around, or puts their head down, while the Hider takes some of the counters and hides them under the cover object.
4. The Guesser looks at the remaining counters and answers the question, “How many are missing?” They can use the number line or five-frame, as well as their addition and subtraction skills, to help determine how many the Hider took away.
5. The Hider reveals the hidden counters and they count them all together.
6. Have students switch the Guesser and Hider roles and play again!


Checks for Understanding

To deepen children’s learning about early math concepts, talk and ask questions while doing this activity together. Here are some examples to get you started.

Counting One-to-One
  • To the Guesser: “Can you touch and count the counters that are left over?”
  • “How many counters are hiding?”
  • “How many counters do you have?”
  • To the Guesser: “How many counters do you have left?”
  • “If I have 5 counters and I want 3, how many should I take away?”
  • “If I have 3 counters and I want 5, how many more do I need?”

Activity Modifications

Once you have tried out the activity, here are some other things you can do. Try these modifications to keep the activity interesting and challenging for students all year.

Introduce a Variation
  • Have the Hider draw number cards showing numerals, dots, or both to determine how many counters to remove.
  • Estimate size of the sets. When the Guesser’s eyes are closed, the Hider can either add or take away some counters. Then the Guesser decides if the new set is larger or smaller. You can use more counters (for example, 20) because children just need to estimate and not count. Encourage children to add or remove more than just a few counters. Support using larger quantities with a ten-frame or a double ten-frame.
  • Use fewer than five counters.
  • The Guesser chooses the starting amount of counters. While the Guesser looks away, the Hider adds more counters to the number line. The Guesser determines how many the Hider added.
  • Use more than five counters for students who are ready to work with larger numbers. Support using larger quantities with a longer number line, ten-frame, or double ten-frame.
  • Give the Guesser five counters of one color or type and five of another color or type. The Hider can take away counters from either or both sets, and the Guesser has to figure out how many of each color were taken. Five-frames or a ten-frame may be helpful for children who are ready for multiple sets of counters but need less of a challenge.

Choosing interesting materials is an easy way to tie in a theme, but make sure they don’t distract attention from the activity. Here are two theme suggestions:

  • Magicians: The Hider is a magician and is going to choose how many coins they want to hide under their hat. The Guesser is the magician’s assistant who will then have to guess how many are hidden. Give the Hider a hat or a printed picture of a hat under which to hide the counters.
  • Feed the Animals: The Hider hides the counters under a stuffed animal and the Guesser figures out how many counters the animal ate.