Sure! Here are a few interesting activities that can help children between the ages of 5 to 6 with the introduction of maths and phonics through brain gym activities:

1. Number Hunt: Hide number cards or small objects with numbers written on them around the room. The child can search for these numbers and place them in the correct order. This activity helps with number recognition and counting skills.

2. Letter Sounds Scavenger Hunt Hide objects around the room that start with different letter sounds. Give the child a list of letters and ask them to find objects that match those sounds. This activity helps with letter recognition and phonics.

3. Pattern Building: Use blocks, beads, or other objects to create simple patterns (e.g., red-blue-red-blue) and ask the child to continue the pattern. This activity helps develop pattern recognition, which is important for both math and reading.

4. Math Magic: Use playing cards or number cards to play simple math games like "War" or "Snap". This helps children practice number recognition and basic addition or subtraction skills.

5. Sensory Math: Fill a tray with sand, rice, or water and bury small objects or number cards in it. Have the child search for and identify the objects or numbers using their fingers. This activity engages their senses while practicing math concepts.

6. Phonics Snack: Use letter-shaped cookie cutters to make alphabet-shaped snacks like sandwiches or cookies. While enjoying the snack, the child can practice saying the sound of the letter.

Remember to make the activities fun and exciting for the to keep them engaged and motivated to learn. Also, always provide positive encouragement and praise their efforts.