Heidi Klum's mommy duties don't ever stop -- no matter what's happening with her and estranged husband Seal.

The supermodel and Project Runway host, 38, made another somber public appearance on Saturday, her second in the week since she and the "Kiss from a Rose" singer, 48, announced their separation after seven years of marriage.

This time, the normally bubbly star kept a straight face as she picked up daughters Lou, 2, and Leni, 4, from karate school in L.A. As she did earlier in the week, Klum -- like Seal, who made numerous promotional appearances last week -- kept her wedding ring on. See more photos from Heidi's somber outing.

"Just because you separate, I don't think you all of a sudden stop loving each other," Seal said last Monday during on a appearance on PBS' Tavis Smiley Show.

In a later chat, Seal also revealed that he and Klum have broken the news of their separation to all four of their kids -- the girls Lou and Leni and sons Henry, 6, and Johan, 5.

"Just explaining to them that things will be different, you know, without going into too much detail," Seal explained of the difficult chat. "But a lot of things won't change."