Seven-year-olds still are at an age where they benefit from learning math concepts with manipulatives. Manipulatives such as base 10 blocks are objects that allow for a hands-on approach to learning. Children learn by doing and engaging their senses when they use base 10 blocks learn place value. Cubes represent "ones," and rods, also called longs, represent a group of 10 "ones" (one group of 10).

Hold up several ones cubes and rods. Ask the children whether anyone has seen blocks like these before. Tell them that these blocks are called base 10 blocks. Hold up a ones cube and say, "This is a ones cube." Hold up a rod and say, "This is a rod."

Draw a cube and a rod on the board. Write "ones cube" under the cube and "rod" under the rod.

Give each child 10 ones cubes and one rod. Tell them to try to find a relationship between the two types of blocks. Allow the children about five minutes to handle and explore the base 10 blocks.

Ask the children if they found a relationship between the two types of blocks. If no one answers that 10 of the ones cubes are the same length (or size) as the rod, show them. Line up the 10 cubes and place the rod on top. Explain that the ones cubes have a value of one, 10 cubes make a rod and the value of a rod is 10.

Write "1" under the words "ones cube" on the board. Write "10" under the word "rod" on the board. Tell the children that these are the other names for the ones cube and the rod.

Pass out the papers with the "ones" and "10s" columns. Tell the children to place all 10 cubes in the "ones" column. Explain that the "ones" column can hold only 10 cubes. If they have more, they have to trade, or exchange, 10 cubes for a rod and put the rod in the "10s" column.

Draw a "10s" and "ones" chart, just like the one on their paper, on the board. Draw 12 cubes in the "ones" column. As you explain the rule again, demonstrate the rule by erasing 10 cubes and drawing a rod in the "10s" column. Tell them, "Now we have one group of 10 (the rod) plus two "ones." Count the number of cubes contained in the rod. Write "10" on the board. Count the number of cubes in the "ones" column. Write "+ 2 = 12" on the board. Ask the children to count the number of cubes in a rod (10), plus the cubes in the "ones." Use more examples until they understand the concept.

Pass out five more cubes to each student. Tell them to place the cubes in the "ones" column. Ask them, "What is the rule for the "ones" column?" If they do not remember, remind them that only 10 cubes can stay in the "ones" column. If they have too many, they need to exchange the 10 cubes for a rod and place the rod in the "10s" column.

Tell the children to put the five extra cubes in the "ones" column and to use the new rule. They should exchange 10 cubes for a rod and place the rod in the "10s" column. Ask them how many cubes are in the "ones" column. Help them to answer five cubes, or five "ones." Ask them how many rods are in the "10s" column. Help them to answer one rod or one "10." Explain the process and demonstrate it on the board.

Use other problems for more practice. Try using more than 20 cubes in the "ones" column, so they have to exchange cubes for more than one rod.

### Things you need

- Cubes and rods from a set of base 10 blocks per student
- Paper, or tagboard, printed with a "10s" column on the left half and a "ones" column on the right
- Chalkboard and chalk, or whiteboard and dry erase marker

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