Students determine the number of cubic units in each irregular shape on this math worksheet.

To determine the number of cubic units in each shape, we need to count the total number of individual cubes that make up each structure. Let's go through each shape step by step.

Shape 1:

- The shape is a rectangular prism with dimensions \(3 \times 4 \times 2\).
- Volume = \(3 \times 4 \times 2 = 24\) cubic units.
- Answer: 24

Shape 2:

- The shape consists of two rectangular prisms stacked on top of each other.
- Bottom layer: \(4 \times 4 \times 1 = 16\) cubic units.
- Top layer: \(4 \times 3 \times 1 = 12\) cubic units.
- Total volume = \(16 + 12 = 28\) cubic units.
- Answer: 28

Shape 3:

- The shape is composed of two separate rectangular prisms.
- Left part: \(3 \times 3 \times 2 = 18\) cubic units.
- Right part: \(1 \times 1 \times 3 = 3\) cubic units.
- Total volume = \(18 + 3 = 21\) cubic units.
- Answer: 21

Shape 4:

- The shape is a rectangular prism with dimensions \(5 \times 3 \times 2\).
- Volume = \(5 \times 3 \times 2 = 30\) cubic units.
- Answer: 30

Shape 5:

- The shape is a rectangular prism with dimensions \(4 \times 3 \times 2\).
- Volume = \(4 \times 3 \times 2 = 24\) cubic units.
- Answer: 24

Shape 6:

- The shape is a rectangular prism with dimensions \(2 \times 2 \times 3\).
- Volume = \(2 \times 2 \times 3 = 12\) cubic units.
- Answer: 12

Shape 7:

- The shape is a combination of two rectangular prisms.
- Bottom layer: \(3 \times 3 \times 1 = 9\) cubic units.
- Top layer: \(2 \times 2 \times 1 = 4\) cubic units.
- Total volume = \(9 + 4 = 13\) cubic units.
- Answer: 13

Shape 8:

- The shape is a combination of three rectangular prisms.
- Bottom layer: \(3 \times 3 \times 1 = 9\) cubic units.
- Middle layer: \(3 \times 2 \times 1 = 6\) cubic units.
- Top layer: \(2 \times 2 \times 1 = 4\) cubic units.
- Total volume = \(9 + 6 + 4 = 19\) cubic units.
- Answer: 19

Shape 9:

- The shape is a combination of two rectangular prisms.
- Main part: \(4 \times 3 \times 2 = 24\) cubic units.
- Extension: \(1 \times 2 \times 1 = 2\) cubic units.
- Total volume = \(24 + 2 = 26\) cubic units.
- Answer: 26

Shape 10:

- The shape is a combination of two rectangular prisms.
- Main part: \(4 \times 3 \times 2 = 24\) cubic units.
- Extension: \(2 \times 2 \times 1 = 4\) cubic units.
- Total volume = \(24 + 4 = 28\) cubic units.
- Answer: 28

Shape 11:

- The shape is a combination of three rectangular prisms.
- Bottom layer: \(3 \times 3 \times 1 = 9\) cubic units.
- Middle layer: \(2 \times 2 \times 1 = 4\) cubic units.
- Top layer: \(1 \times 1 \times 3 = 3\) cubic units.
- Total volume = \(9 + 4 + 3 = 16\) cubic units.
- Answer: 16

Shape 12:

- The shape is an L-shaped structure.
- Main part: \(4 \times 3 \times 2 = 24\) cubic units.
- Extension: \(1 \times 2 \times 2 = 4\) cubic units.
- Total volume = \(24 + 4 = 28\) cubic units.
- Answer: 28

Final Answers:

\[
\boxed{24, 28, 21, 30, 24, 12, 13, 19, 26, 28, 16, 28}
\]