Star formation history of the Sextans-type dSph, sex156, shown in Fig. 2 compared with the Sextans model in isolation. The interaction of the dSph and the MW begins at the dashed line for each model. Perigalacticons are indicated with a dotted line for each interaction model. The cessation of star formation clearly occurs around perigalacticon for models that have experienced three and two perigalacticon passages. The slight increase in star formation observed at the start of the interaction is due to a numerical issue. This increase in star formation, however, accounts for less than 5% of the cumulative star formation inside a dwarf galaxy.