In a large bowl, stir together the whole wheat flour, all-purpose flour and salt. Add enough water to make soft dough that is elastic but not sticky. Knead the dough on a lightly floured surface until it is smooth. Divide into 10 parts, or less if you want bigger breads. Roll each piece into a ball. Let rest for a few minutes.
Heat a skillet over medium heat until hot.
On a lightly floured surface, use a floured rolling pin to roll out the balls of dough until very thin like a tortilla. When the pan is hot, put a chapati on it. Cook until the underside has brown spots, about 20 seconds, then flip and cook on the other side.
Wait 10 seconds (approximately) after the second flip and then use a folded kitchen towel to gently press the Chapati around its edges. This will encourage it to puff out!