Creating a themed 4-week lesson plan for children aged 2-4 years that includes letters, numbers, and sensory play requires activities that are engaging, educational, and appropriate for their developmental stage. Here's a structured plan:

Week 1: Nature Explorers

Focus: Introducing nature through letters, numbers, and sensory experiences.

Day 1: Letters - "A for Acorn"

• Supplies: Paper, acorns, non-toxic paint.

• Activity: Dip acorns in paint and stamp them on paper to form the letter 'A'.

Day 2: Numbers - Counting Leaves

• Supplies: Various leaves, number flashcards (1-5).

• Activity: Match the number of leaves to the corresponding number on the flashcards.

Day 3: Sensory Play - Nature Exploration Bin

• Supplies: Bin, soil, twigs, leaves, magnifying glass.

• Activity: Let children explore the textures and colors in the bin.

Week 2: Under the Sea

Focus: Exploring ocean life using letters, numbers, and sensory activities.

Day 1: Letters - "B for Boat"

• Supplies: Construction paper, straws, tape.

• Activity: Create a paper boat and decorate it with the letter 'B'.

Day 2: Numbers - Fish Counting

• Supplies: Fish cutouts, small net or scoop, water table or large bin with water.

• Activity: Catch and count fish cutouts from the water.

Day 3: Sensory Play - Ocean Sensory Bin

• Supplies: Bin, water, blue food coloring, ocean animal toys.

• Activity: Explore the 'ocean' with hands, finding different sea creatures.

Week 3: Space Adventure

Focus: Learning about space through letters, numbers, and sensory play.

Day 1: Letters - "S for Stars"

• Supplies: Black paper, star stickers, white chalk.

• Activity: Stick stars on paper and draw the letter 'S' with chalk.

Day 2: Numbers - Moon Rock Counting

• Supplies: Small rocks, silver paint, number cards.

• Activity: Paint rocks to look like moon rocks and count them based on the numbers shown on the cards.

Day 3: Sensory Play - Galaxy Discovery Bin

• Supplies: Bin, black beans, glow-in-the-dark stars, small space toys.

• Activity: Explore the galaxy bin and discuss space objects.

Week 4: Jungle Journey

Focus: A jungle-themed exploration of letters, numbers, and sensory activities.

Day 1: Letters - "J for Jungle"

• Supplies: Green paper, markers, animal stickers.

• Activity: Create a jungle scene and highlight the letter 'J'.

Day 2: Numbers - Jungle Animal Sorting

• Supplies: Toy jungle animals, sorting bins, number labels.

• Activity: Sort animals into bins based on the number label.

Day 3: Sensory Play - Jungle Safari Bin

• Supplies: Bin, rice dyed green, toy animals, small trees or plants.

• Activity: Go on a 'safari' and find different animals in the bin.

Each activity is designed to be interactive and suitable for young children, encouraging learning through play and exploration.