Math Crafts – Crab Counting


crab make

This Let’s Read Math activity was inspired by the book One is a Snail, Ten is a Crab by April Pulley Sayre and Jeff Sayre.

pwa-06 one is snail (1)

The book starts by explaining that a snail has just one foot.  Then the snail is used to “add one.”  For example.  If “One is a snail,” and “Two is a person,” then “Three is a person and a snail.”  We extended the activity so that children solve math problems by counting the number of feet on other animals that they know.   We ask them. “How many feet do other animals have?”  Then have them solve problems like: “If one ladybug has 6 feet, how many feet are on 2 ladybugs?”

Another critical piece of information is that all crabs have ten feet – two claws, 2 back feet for swimming, and 6 feet for walking!  This leads to the concept of counting by tens.  If one crab is 10, then 2 crabs are 20, 3 crabs are 30, etc.   Make paper plate crab “puppets” with ten legs, then have children use their crab puppets to practice counting by tens!

The next part of the lesson involves using pictures of animals with different numbers of feet to practice addition, multiplication and beginning ALGEBRA!

MATERIALS FOR MAKING THE CRAB:

  • One red paper plate cut in half. (Need scissors.)
  • Red cardstock or colored paper to cut out legs and head. (Click here to get a .pdf of the crab parts.)
  • Scotch tape to attach legs.
  • Two brass fasteners to attach the claws.
  • Two googly eyes and a glue stick.

DIRECTIONS FOR THE CRAB:

1. Cut the plate in half.

2. Cut out two claws, six side legs, the two back legs, and a heart-shaped head.

3. Tape down the side legs and back legs on one of the half-plates.

Then tape down the head on the flat upper side of the same half-plate.

4. Put the second half-plate on top of the bottom half-plate, to hide the scotch tape.

5. Insert the claws between the two plates.

Attach them by using a brass fastener that goes through the top plate, the claw, and the bottom plate. This allows the claws to move. (To make it easier to insert the brass fastener, you may want to use a hole puncher.)

Finally, use the glue stick to glue down the googly eyes.

6. Put your hand between the plates to make a puppet.

Have your puppet count by tens!

CRAB ALGEBRA

westchestr crabs08 (1) crab algebra

DIRECTIONS FOR DOING ADDITION, MULTIPLIICATION, AND ALGEBRA

1. Have fun thinking about the number of feet on different animals.

Make up a set of animal pictures and tell how many feet on each animal.

2. Practice Addition.

What if you had a cat and a dog?  (4+4=8)

Or a spider and a bird? (8+2=10)

Or a crab and a fish? (10+0=10)

3. Practice Multiplication.

What if you had 3 cats? (3×4=12)

Or 5 ladybugs? (5×6=30)

Or 8 spiders? (8×8=64)

Or 6 dogs and 10 snails? (6×4)+(10×1) = 34

4. Practice Algebra.

Use variables to record your discoveries.

If C=cat and D=dog, C+D=8,   or  3C=12.

If Sn=Snail, and Cr=Crab, 5Cr + 1Sn = 51.

GET A PACKET

Purchase a Crab Lesson Packet on the Let’s Read Math website.  It includes:

  •      one copy of the book
  •      the black line master for making the crab
  •      a lesson outline
  •      a collection of animal pictures for practicing addition, multiplication, or algebra
  •      two worksheets for practicing “Animal Algebra.”

 

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