Entrelac knitting
Short rows build interlocking squares with picked-up edges.
Counted practice swatch
For a first sampler cast on 12 stitches in three groups of 4. Base triangle: k2, turn, p2; k3, turn, p3; k4. Repeat on the next two groups.
Work the repeat
Left edge triangle: p2, turn k2; p1, p2tog, turn k2; p1, p2tog, turn k2; p1, p2tog. For each following wrong-side square pick up and purl 4 along a base triangle edge; turn k4; then [p3, p2tog with the next waiting stitch, turn k4] until 4 waiting stitches are consumed.
Read the fabric
The picked-up group stays four stitches while its p2tog attaches it to the adjacent group. Work the corresponding right-side tier with k3, ssk joins. Finish with short-row triangles rather than leaving a stepped edge.