Children who have difficulty with /l/ generally replace the sound with /w/ e.g. lion becomes wion. The error is made due to incorrect placement of the mouth to produce the sound.
Here are some ways to help a child produce the /l/ sound:
1. Instruct the child to put the tip of their tongue behind their top teeth (see figure 1). Check the position with a mirror. Ask the child to raise and lower their tongue several time to practice moving their tongue into the correct position. Ask the child to say /la/. Encourage the child to 'smile' as they say the sound to make sure that their lips do not move into a rounded /w/ position.
2. Have the child practice this sequence of sounds /t/-/d/-/n/-/l/. Shape /l/ from /t/ e.g. /ta-la/, then /d/ e.g. /da-na/ and then /n/ e.g. /na-la/.
3. Describe to the child the different mouth positions for /l/ and /w/. /l/ is a sound made with your tongue behind your top teeth; /w/ is a sound made by your lips 'kissing lips'. Practice moving from a /l/ to a /w/ sound so that the child can feel the difference in mouth placement. Use this information when practicing saying /l/ words e.g. What did your mouth do at the start of the word - was your tongue up or did you use your kissing lips?
Figure 1. Tongue position for /l/.