Reese Witherspoon's kids think she's cool because she knows how to use Snapchat.

Reese Witherspoon

Reese Witherspoon

The 40-year-old actress - who has Ava, 17, and Deacon, 13, with ex-husband Ryan Phillippe and four-year-old Tennessee with spouse Jim Toth - admits the youngsters are impressed with her knowledge of the social media app because "most moms" don't know how it works.

She said: "At least I know how to work Snapchat. I think, you know, most moms don't.

"[My kids] are like, 'You actually know what Snapchat is and you're actually sending us a lot of Snapchats.' So, maybe that's kind of a cool thing."

In Reese's upcoming movie 'Sing', the actress voices the pig Rosita, who gave up her singing dreams to raise her 25 kids, but returns to performing, and Reese loved the fact the movie showed her character has an identity away from just being a parent.

She told 'Entertainment Tonight': "I think that there's something beautiful about the idea that your mom is a person too.

"Beyond being just a mom, [Rosita] has her own dreams and desires so... the film kind of explores that through my character."

But the film required Reese to tackle a number of songs, and admitted she found Taylor Swift's 'Shake It Off' and Katy Perry's 'Firework' harder than she expected, which she confided into the two stars.

She said: "I actually ran into both of them as I was doing each song.

"I said to Taylor, 'Oh my God, I have a new appreciation of how hard it is to sing 'Shake It Off'. when I had to actually do it. She was like, 'Yeah, you know, I make it look easy but it's really hard,'" she said.

"'Firework' is a really hard song to sing. [Katy] was like, 'That's hard.' But I just did the best I could."

Though Reese - who picked up an Oscar for her musical turn as June Carter Cash in 'Walk the Line' in 2005 - loves to sing, she insists her latest movie hasn't made her want to embark on a musical career.

She added: "I'm supposed to be the mom singing the songs, so they don't have anything to worry about. I'm not cutting an album any time soon!"

And the blonde beauty previously admitted her kids get embarrassed when she sings.

She said: "I think I embarrass them terribly when I try to sing Drake songs. I don't stop singing. I enjoy it."

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